Products

Alpha crystallins are composed of two gene products ; alpha-A and alpha-B, for acidic and basic, respectively. Alpha crystallins can be induced by heat shock and are members of the small heat shock protein (sHSP also known as the HSP20). They act as molecular chaperones and hold them in in large soluble aggregates. These heterogeneous aggregates consist of 30-40 subunits; the alpha-A and alpha-B subunits have a 3:1 ratio, respectively. Two additional function of a-crystallins are an autokinase activity and participation in the intracellular architecture. Alpha-B is expressed widely in many tissues and organs and occurs in many neurological diseases.

Beta-crystallin A4 (CRYBA4) is a member of the beta/gamma-crystallin family which are the dominant structural components of the vertebrate eye lens. Beta-crystallins construct aggregates of various sizes and are able to self-associate to form dimers or to form heterodimers with other beta-crystallins. The CRYBA4 gene being a beta acidic group member is part of a gene cluster with beta-B1, beta-B2, and beta-B3.

Crystallins are the main structural proteins of the vertebrate eye lens, where they maintain the transparency and refractive index of the lens. Crystallins are divided into 3 fprotein families, α, β, & γ families. Because lens central fiber cells lose their nuclei during development, these crystallins are prepared and then retained throughout life, making them extremely stable proteins. CRYBB1 is a beta basic group member and undergoes extensive cleavage at its N-terminal extension during lens maturation.

CRYGC is a member of the beta/gamma-crystallin family. Mammalian lens crystallins are distributed into alpha, beta, and gamma families; beta and gamma crystallins are also considered as a superfamily. Gamma-crystallins are a homogeneous group of extremely symmetrical, monomeric proteins usually missing connecting peptides and terminal extensions and are differentially regulated after early development. Three pseudogenes (gamma-E,F,G) and four gamma-crystallin genes (gamma-A,B,C,D) are structured in a genomic sector as a gene cluster. Gamma-crystallins are involved in cataract formation as a result of aging or mutations in specific genes. Mutations in CRYGC result in cataract Coppock-like (CCL) and cataract autosomal dominant (ADC).

CRYGD is a member of the beta/gamma-crystallin family. Crystallins are the principal structural components of the vertebrate eye lens. The mammalian lens crystallins are divided into alpha, beta, and gamma families. Gamma-crystallins are involved in cataract formation. Defects in the CRYGD gene are responsible for cataract autosomal dominant (ADC), cataract congenital non-nuclear polymorphic autosomal dominant (CCP), cataract congenital cerulean type 3 (CCA3) and cataract crystalline aculeiform (CACA).

CRYGD is a member of the beta/gamma-crystallin family. Crystallins are the principal structural components of the vertebrate eye lens. The mammalian lens crystallins are divided into alpha, beta, and gamma families. Gamma-crystallins are involved in cataract formation. Defects in the CRYGD gene are responsible for cataract autosomal dominant (ADC), cataract congenital non-nuclear polymorphic autosomal dominant (CCP), cataract congenital cerulean type 3 (CCA3) and cataract crystalline aculeiform (CACA).

Crystallin gamma N (CRYGN) is a member of the Crystallins family. Crystallins are the main proteins of the vertebrate eye lens, where they preserve the transparency and refractive index of the lens. CRYGN is unique in the way that it has both beta and gamma crystallin protein motifs. The CRYGN is differentially controlled after early development, and is involved in cataract creation due to either age-related protein degradation or genetic mutation.

Mammalian crystallins which are water soluble structural proteins located in the vertebrate eye are classified in three forms, labeled alpha, beta and gamma. Crystallins, the primary components of the lens, raise the refractive index of the eye all through the accommodation by creating high-molecular weight aggregates that maintain transparency. CRYGS is a monomer that does not aggregate. CRYGS encodes the most substantial gamma-crystallin in adult eye lens tissue. Gamma-crystallins has a part in cataract formation due to aging or mutations in specific genes,

Crystallin, Mu (CRYM) is a taxon-specific crystallin protein which binds NADPH and has sequence similarity to bacterial ornithine cyclodeaminases. CRYM doesn’t perform a structural role in lens tissue; instead CRYM binds thyroid hormone for possible regulatory or developmental roles. CRYM gene mutations are linked with autosomal dominant non-syndromic deafness. CRYM specifically catalyzes the reduction of imine bonds in brain substrates which may include cystathionine ketamine and lanthionine ketamine.

Crystallin Zeta, also known as CRYZ, Binds NADP and participates in a one-electron transfer process. CRYZ takes part in the detoxification of xenobiotics and Interacts with (AU)-rich elements (ARE) in the 3'-UTR of target mRNA species. CRYZ improves the mRNA coding for BCL2.

Quinone Oxidoreductase (CRYZL1) is a protein that has sequence similarity to zeta crystalline. CRYZL1 has NADPH-dependent quinone reductase activity distinct from other known quinone reductases, and may have a role as a pH response element-binding protein. CRYZL1 contains an NAD(P)H binding site. CRYZL1 is expressed at different levels in the heart, brain, skeletal muscle, kidney, pancreas, liver and lung. CRYZL1 is present at low levels in human lens tissue.

Citrate synthase also known as CS is a Krebs tricarboxylic acid cycle enzyme which catalyzes the synthesis of citrate from oxaloacetate and acetyl coenzyme A. CS is present in almost all cells capable of oxidative metabolism. CS is nuclear encoded and transported into the mitochondrial matrix, where the mature form is found. The diseases related to CS are: critical illness polyneuropathy and mitochondrial cardiomyopathy.

Chondrosarcoma Associated Gene 1 (CSAG1) belongs to a family of tumor antigens. The CSAG1 protein is expressed in chondrosarcomas, but may also be expressed in normal tissues such as testis.

Cold shock domain-containing protein C2 (CSDC2) is RNA-binding factor that binds specifically to the very 3'-UTR ends of both histone H1 and H3. 3 mRNAs encompass the polyadenylation signal. The CSDPs (cold shock domain containing proteins) are one group of the evolutionarily conserved nucleic acid-binding proteins extensively distributed in bacteria, plants, animals, and involved in a variety of cellular processes, including adaptation to low temperature, cellular growth, nutrient stress and stationary phase. CSDC2 has a central role in the negative regulation of histone variant synthesis in the developing brain.

GM-CSF Receptor Alpha (CSF2RA) is the alpha subunit of the heterodimeric receptor for colony stimulating factor 2, a cytokine which controls the production, differentiation, and function of granulocytes and macrophages. CSFR2 is also a member of the cytokine family of receptors. In addition, this gene is found in the pseudoautosomal region (PAR) of the X and Y chromosomes. Multiple transcript variants encoding various isoforms have been found for this gene, while some of the isoforms being membrane-bound and others being soluble. Diseases associated with CSF2RA include surfactant metabolism dysfunction, pulmonary 4, and csf2ra-related pulmonary surfactant metabolism dysfunction.

GM-CSF Receptor Alpha (CSF2RA) is the alpha subunit of the heterodimeric receptor for colony stimulating factor 2, a cytokine which controls the production, differentiation, and function of granulocytes and macrophages. CSFR2 is also a member of the cytokine family of receptors. In addition, this gene is found in the pseudoautosomal region (PAR) of the X and Y chromosomes. Multiple transcript variants encoding various isoforms have been found for this gene, while some of the isoforms being membrane-bound and others being soluble. Diseases associated with CSF2RA include surfactant metabolism dysfunction, pulmonary 4, and csf2ra-related pulmonary surfactant metabolism dysfunction.

GM-CSF Receptor Beta, also known as CSF2RB is a member of the type I cytokine receptor family. CSF2RB is a high affinity receptor for interleukin-3, interleukin-5 as well as granulocyte-macrophage colony-stimulating factor. CSF2RB unique form of receptor assembly applies also to IL-3 and IL-5 receptors, providing a structural basis for understanding their activation mechanism which is essential for the development of therapeutics.

C-Src Tyrosine Kinase, also known as CSK, regulates cell growth, migration, differentiation, and immune response. CSK Phosphorylates tyrosine residues located in the C-terminal tails of Src-family kinases. CSK is a protein coding gene which suppresses signaling by several surface receptors. Among CSK's related pathways are PI-3K cascade and Signaling by FGFR.

C-Src Tyrosine Kinase, also known as CSK, regulates cell growth, migration, differentiation, and immune response. CSK Phosphorylates tyrosine residues located in the C-terminal tails of Src-family kinases. CSK is a protein coding gene which suppresses signaling by several surface receptors. Among CSK's related pathways are PI-3K cascade and Signaling by FGFR.

Beta-casein precursor (CSN2) is a member of the beta-casein family. CSN2 has an imperative role in determination of the surface properties of the casein micelles. CSN2 is specific to mammary glands and is secreted in milk.

Caseine Kinase 1 alpha belongs is a member of the protein kinase superfamily, CK1 Ser/Thr protein kinase family, Casein kinase I subfamily. The CK1 isoforms - alpha, beta, gamma, delta, epsilon and their splice variants are involved in diverse cellular processes including membrane trafficking, circadian rhythm, cell cycle progression, chromosome segregation, apoptosis and cellular differentiation. Possibly CSNK1A1 can phosphorylate a large number of proteins and is involved in Wnt signaling where it phosphorylates CTNNB1 on Ser45. CSNK1A1 also interacts with the Axin complex.

Caseine Kinase 1 alpha belongs is a member of the protein kinase superfamily, CK1 Ser/Thr protein kinase family, Casein kinase I subfamily. The CK1 isoforms - alpha, beta, gamma, delta, epsilon and their splice variants are involved in diverse cellular processes including membrane trafficking, circadian rhythm, cell cycle progression, chromosome segregation, apoptosis and cellular differentiation. Possibly CSNK1A1 can phosphorylate a large number of proteins and is involved in Wnt signaling where it phosphorylates CTNNB1 on Ser45. CSNK1A1 also interacts with the Axin complex.

Casein kinase I gene family members take part in the control of cytoplasmic and nuclear processes, including DNA replication and repair. Casein Kinase 1 Delta (CSNK1D) is a member of the casein kinase I (CKI) gene family. CSNK1D is a vital serine/threonine-protein kinase which regulates diverse cellular growth and survival processes including Wnt signaling and circadian rhythms. CSNK1D phosphorylates a great amount of proteins.

The Casein kinase 2 (EC 2.7.11.1) is a serine/threonine-selective protein kinase that is a tetramer of two alpha subunits and two beta subunits. The alpha subunits have the catalytic kinase domain. Casein kinase 2 has been implicated in cell cycle control, DNA repair, regulation of the circadian rhythm and other cellular processes. Casein kinase 2 activity has been reported to be activated following Wnt signaling pathway activation. A Pertussis toxin-sensitive G protein and Disheveled appear to be an intermediary between Wnt-mediated activation of the Frizzled receptor and activation of casein kinase 2. Mice that lack casein kinase 2 alpha prime have a defect in the morphology of developing sperm.

The Casein kinase 2 (EC2.7.11.1) is a serine/threonine-selective protein kinasethat is a tetramer of two alpha subunits and two beta subunits. The alpha subunits have the catalytic kinase domain. Casein kinase 2 has been implicated in cell cyclecontrol, DNA repair, regulation of the circadian rhythmand other cellular processes. Casein kinase 2 activity has been reported to be activated following Wnt signaling pathwayactivation. A Pertussis toxin-sensitive G proteinand Disheveled appear to be an intermediary between Wnt-mediated activation of the Frizzled receptor and activation of casein kinase 2.
Mice that lack casein kinase 2 alpha prime have a defect in the morphology of developing sperm.

The Casein kinase 2 (EC2.7.11.1) is a serine/threonine-selective protein kinasethat is a tetramer of two alpha subunits and two beta subunits. The alpha subunits have the catalytic kinase domain. Casein kinase 2 has been implicated in cell cyclecontrol, DNA repair, regulation of the circadian rhythmand other cellular processes.
Casein kinase 2 activity has been reported to be activated following Wnt signaling pathwayactivation. A Pertussis toxin-sensitive G proteinand Disheveled appear to be an intermediary between Wnt-mediated activation of the Frizzled receptor and activation of casein kinase 2.
Mice that lack casein kinase 2 alpha prime have a defect in the morphology of developing sperm.

Casein kinase 2 subunit alpha (CSNK2A2) controls numerous cellular processes, such as cell cycle progression, apoptosis and transcription, as well as viral infection. CSNK2A2 protein functions as a regulatory node which integrates and coordinates numerous signals leading to an appropriate cellular response.

Casein Kinase 2 beta (CSNK2B) is a ubiquitous Ser/Thr kinase expressed in all eukaryotes. CSNK2Bis atetramer comprised of 2 catalytic kinase domains, alpha subunits and 2 identical regulatory beta subunits.CSNK2Btakes part incell cycle control, DNA repair,regulation of the circadian rhythm and other cellularprocesses. The beta subunit itself confers stability to the CK2 alpha subunitand is involved in activity and substrate specificity but does not have kinase activity.

Casein Kinase 2 also called CK2 (also called PKCK2) is a ubiquitous Ser/Thr kinase expressed in all eukaryotes. CK2 is a tetramer composed of two catalytic kinase domains, alpha subunits, and two identical regulatory beta subunits. It has been implicated in cell cycle control, DNA repair, regulation of the circadian rhythm, and other cellular processes. The beta subunit itself does not have kinase activity, but confers stability to the CK2 alpha subunit and is involved in activity and substrate specificity.

CSRP2 belongs to the CSRP family. CSRP2 holds 2 LIM zinc-binding domains that take part in regulatory processes essential for development and cellular differentiation. Additionally, CSRP2 is involved in the development of the embryonic vascular system.

Cystatin-SN (CST1) belongs to the type 2 salivary cystatin family found in a variety of fluids and secretions, including plasma, tears, and saliva. The cystatin superfamily includes proteins which contain multiple cystatin-like sequences. Some of the members are active cysteine protease inhibitors, whereas others have lost or possibly never developed this inhibitory activity. CST1 is up-regulated in cancerous lesions of gastric cancer tissues compared to noncancerous regions, in addition clinicopathological analysis revealed a significant correlation between high expression of CST1.

Cystatin 11 (CST11) is a member of the Cystatin family. The Cystatin superfamily is comprised of proteins with multiple cystatin-like sequences. Several family members are active cysteine protease inhibitors, other family members have lost or perhaps never developed this inhibitory activity. The Cystatin superfamily consists of three inhibitory families, including the type 1 cystatins (stefins), type 2 cystatins and the kininogens. The type 2 cystatin proteins are a class of cysteine proteinase inhibitors found in a variety of human fluids and secretions. The majority of the type 2 cystatin genes and pseudogenes are contained in the cystatin locus on chromosome 20. CST11 is located in the cystatin locus and encodes an epididymal-specific protein whose specific function has not been verified yet.

Cystatins are a superfamily of cysteine proteinase inhibitors found in both plants and animals. They comprise a group of proteinase inhibitors, widely distributed in tissues and body fluids, and form tight complexes with cysteine proteases such as cathepsin B, H, L and S. Cystatin C, a secreted molecule of this family, is of interest from biochemical, medicine and evolutionary points of view. Cystatin C, with molecular weight of 13260 Da, is composed of 120 amino acids, lacks carbohydrate and has two disulfide bridges located near the carboxyl terminus. Cystatin C is increased in patients with malignant diseases, and is related to the insufficiency of renal function and appears to be a better marker than creatinine. On the other hand, low levels of cystatin C involve cause the breakdown of the elastic laminae and, subsequently, the atherosclerosis and abdominal aortic aneurysm.

Cystatin C is part to the cystatin protein family, which has members with various cystatin-like sequences. Part of the proteins has the ability to act as active cysteine protease inhibitors, other members has lost or never had the ability. Three sub members of the cystatin protein family are the type 1 cystatins, type 2 cystatins & kininogens. The locus in chromosome twenty holds the most type 2 cystatin genes. Cystatin C can be found in the cystatin locus, it is the most common extracellular inhibitor of cysteine proteases, that is available in big volumes in biological fluids and exist in every tissue in the body.

Cystatins are a superfamily of cysteine proteinase inhibitors found in both plants and animals. They comprise a group of proteinase inhibitors, widely distributed in tissues and body fluids, and form tight complexes with cysteine proteases such as cathepsin B, H, L and S. Cystatin C, a secreted molecule of this family, is of interest from biochemical, medicine and evolutionary points of view. Cystatin C is increased in patients with malignant diseases, and is related to the insufficiency of renal function and appears to be a better marker than creatinine. On the other hand, low levels of cystatin C involve cause the breakdown of the elastic laminae and subsequently, the atherosclerosis and abdominal aortic aneurysm.

Cystatins are a superfamily of cysteine proteinase inhibitors found in both plants and animals. They comprise a group of proteinase inhibitors, widely distributed in tissues and body fluids, and form tight complexes with cysteine proteases such as cathepsin B, H, L and S. Cystatin C, a secreted molecule of this family, is of interest from biochemical, medicine and evolutionary points of view. Cystatin C, with molecular weight of 13260 Da, is composed of 120 amino acids, lacks carbohydrate and has two disulfide bridges located near the carboxyl terminus. Cystatin C is increased in patients with malignant diseases, and is related to the insufficiency of renal function and appears to be a better marker than creatinine. On the other hand, low levels of cystatin C involve cause the breakdown of the elastic laminae and, subsequently, the atherosclerosis and abdominal aortic aneurysm.

Cystatins are a superfamily of cysteine proteinase inhibitors found in both plants and animals. They comprise a group of proteinase inhibitors, widely distributed in tissues and body fluids, and form tight complexes with cysteine proteases such as cathepsin B, H, L and S. Cystatin C, a secreted molecule of this family, is of interest from biochemical, medicine and evolutionary points of view. Cystatin C, with molecular weight of 13260 Da, is composed of 120 amino acids, lacks carbohydrate and has two disulfide bridges located near the carboxyl terminus. Cystatin C is increased in patients with malignant diseases, and is related to the insufficiency of renal function and appears to be a better marker than creatinine. On the other hand, low levels of cystatin C involve cause the breakdown of the elastic laminae and, subsequently, the atherosclerosis and abdominal aortic aneurysm.

Cystatins are a superfamily of cysteine proteinase inhibitors found in both plants and animals. They comprise a group of proteinase inhibitors, widely distributed in tissues and body fluids, and form tight complexes with cysteine proteases such as cathepsin B, H, L and S. Cystatin C, a secreted molecule of this family, is of interest from biochemical, medicine and evolutionary points of view. Cystatin C, with molecular weight of 13260 Da, is composed of 120 amino acids, lacks carbohydrate and has two disulfide bridges located near the carboxyl terminus. Cystatin C is increased in patients with malignant diseases, and is related to the insufficiency of renal function and appears to be a better marker than creatinine. On the other hand, low levels of cystatin C involve cause the breakdown of the elastic laminae and, subsequently, the atherosclerosis and abdominal aortic aneurysm.

Cystatins are a superfamily of cysteine proteinase inhibitors found in both plants and animals. They comprise a group of proteinase inhibitors, widely distributed in tissues and body fluids, and form tight complexes with cysteine proteases such as cathepsin B, H, L and S. Cystatin C, a secreted molecule of this family, is of interest from biochemical, medicine and evolutionary points of view. Cystatin C, with molecular weight of 13260 Da, is composed of 120 amino acids, lacks carbohydrate and has two disulfide bridges located near the carboxyl terminus. Cystatin C is increased in patients with malignant diseases, and is related to the insufficiency of renal function and appears to be a better marker than creatinine. On the other hand, low levels of cystatin C involve cause the breakdown of the elastic laminae and, subsequently, the atherosclerosis and abdominal aortic aneurysm.

Cystatins are a superfamily of cysteine proteinase inhibitors found in both plants and animals. They comprise a group of proteinase inhibitors, widely distributed in tissues and body fluids, and form tight complexes with cysteine proteases such as cathepsin B, H, L and S. Cystatin C, a secreted molecule of this family, is of interest from biochemical, medicine and evolutionary points of view. Cystatin C, with molecular weight of 13260 Da, is composed of 120 amino acids, lacks carbohydrate and has two disulfide bridges located near the carboxyl terminus. Cystatin C is increased in patients with malignant diseases, and is related to the insufficiency of renal function and appears to be a better marker than creatinine. On the other hand, low levels of cystatin C involve cause the breakdown of the elastic laminae and, subsequently, the atherosclerosis and abdominal aortic aneurysm.

Cystatins are a superfamily of cysteine proteinase inhibitors found in both plants and animals. They comprise a group of proteinase inhibitors, widely distributed in tissues and body fluids, and form tight complexes with cysteine proteases such as cathepsin B, H, L and S. Cystatin C, a secreted molecule of this family, is of interest from biochemical, medicine and evolutionary points of view. Cystatin C, with molecular weight of 13260 Da, is composed of 120 amino acids, lacks carbohydrate and has two disulfide bridges located near the carboxyl terminus. Cystatin C is increased in patients with malignant diseases, and is related to the insufficiency of renal function and appears to be a better marker than creatinine. On the other hand, low levels of cystatin C involve cause the breakdown of the elastic laminae and, subsequently, the atherosclerosis and abdominal aortic aneurysm.

Cystatins are a superfamily of cysteine proteinase inhibitors found in both plants and animals. They comprise a group of proteinase inhibitors, widely distributed in tissues and body fluids, and form tight complexes with cysteine proteases such as cathepsin B, H, L and S. Cystatin C, a secreted molecule of this family, is of interest from biochemical, medicine and evolutionary points of view. Cystatin C, with molecular weight of 13260 Da, is composed of 120 amino acids, lacks carbohydrate and has two disulfide bridges located near the carboxyl terminus. Cystatin C is increased in patients with malignant diseases, and is related to the insufficiency of renal function and appears to be a better marker than creatinine. On the other hand, low levels of cystatin C involve cause the breakdown of the elastic laminae and, subsequently, the atherosclerosis and abdominal aortic aneurysm.

CST4 is a member of the cystatin superfamily which contains proteins that hold multiple cystatin-like sequences. Several family members are active cysteine protease inhibitors, whereas others have lost or possibly never attained this inhibitory activity. CST4 strongly inhibits papain (non-competitively) and ficin, partially inhibits stem bromelain and bovine cathepsin C, however does not inhibit porcine cathepsin B or clostripain.

CST4 is a member of the cystatin superfamily which contains proteins that hold multiple cystatin-like sequences. Several family members are active cysteine protease inhibitors, whereas others have lost or possibly never attained this inhibitory activity. CST4 strongly inhibits papain (non-competitively) and ficin, partially inhibits stem bromelain and bovine cathepsin C, however does not inhibit porcine cathepsin B or clostripain.

Cystatin 5 (CST5) is a novel member of the cystatin superfamily, which encompasses proteins that contain multiple cystatin-like sequences. Some members are active cysteine protease inhibitors, while others have lost or possibly never had this inhibitory activity. The superfamily is comprised of 3 inhibitory families: the type 1 cystatins (stefins), type 2 cystatins and the kininogens. Type 2 cystatin proteins are a class of cysteine proteinase inhibitors found in various human fluids and secretions.

CST6 belongs to the type 2 cystatin family. Unlike other family members that act as active cysteine protease inhibitors, CST6 restrain the inhibition of cathepsin B but is not active against cathepsin C. CST6 are secretable proteins that influence osteogenesis and bone resorption, regulation of the hepatocyte growth factor receptors, and the response to systemic inflammation.

Cystatin E/M or CST6 is part of the cystatin type 2 family. Part of the cystatin type 2 family members can act as cysteine protease inhibitors, whereas cystatin E/M regulates cathepsin B inhibitors and not cathepsin C. cystatin E/M is a protein the when secreted, has an effect on osteogenesis and bone resorption, insulin regulation, response to systemic inflammation & hepatocyte growth factor receptors.

Cystatin 7 (CST7) is a glycosylated cysteine protease inhibitor with a putative role in immune regulation through inhibition of a unique target in the hematopoietic system. Cystatin-7 is comprised of multiple cystatin-like sequences. The superfamily is comprised of 3 inhibitory families: the type 1 cystatins (stefins), type 2 cystatins and the kininogens. Some members are active cysteine protease inhibitors, while others have lost or possibly never had this inhibitory activity. Type 2 cystatin proteins are a class of cysteine proteinase inhibitors found in various human fluids and secretions. CST7 protein expression has been observed in numerous human cancer cell lines established from malignant tumors.

CST9 belongs to the CRES (cystatin-related epididymal spermatogenic) subfamily. The CRES (cystatin-related epididymal spermatogenic) protein outlines a new subgroup in the family 2 cystatins of the cystatin superfamily. A few members are active cysteine protease inhibitors, however others have lost or possibly never developed this inhibitory activity. CST9 takes part in hematopoietic differentiation or inflammation and is expressed in heart, placenta, lung, liver, skeletal muscle and pancreas. CST9 is upregulated by LPS in several cancer cell lines, such as promyelocytic leukemia (HL-60) and myelomonocytic leukemia.

Cystatin-A is the intracellular inhibitor of cysteine proteinase cathepsin B (CatB) and belongs to family 1 of the cystatin superfamily of inhibitor proteins. CSTA is a stefin that functions as a cysteine protease inhibitor, forming tight complexes with papain and the cathepsins B, H, and L. It has been proposed that extracellular CatB together with other classes of proteinases are all subjected to a cascade-like manner of activation. CatB and its inhibitor Cystatin-A are involved in degradation of extracellular matrix proteins during tissue remodeling. CSTA is one of the precursor proteins of cornified cell envelope in keratinocytes and plays a role in epidermal development and maintenance. Cystatin-A has been reported to be found in high concentrations in epithelial cells, polymorphonuclear leukocytes and lymphoid tissue. Stefins may be used as prognostic and diagnostic tools for cancer.