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RAC2 is a small signaling G protein/GTPase which is part of the RAS superfamily of small GTP-binding proteins which regulate cell growth, actin cytoskeletal organization, cell proliferation, survival, cell cycle progression, gene transcription rgulation and the activation of protein kinases. RAC2 cycles between an active gtp-bound and inactive gdp-bound state. In active state, RAC2 binds to a variety of effector proteins to regulate cellular responses, such as secretory processes, phagocytose of apoptotic cells and epithelial cell polarization. RAC2 is involved in the regulation of the nadph oxidase.

CD14 (also known lipopolysaccharide (LPS) receptor) is expressed strongly on monocytes and macrophage and weakly on the surface of neutrophils. CD14 is anchored to cells by linkage to glycosylphosphatidylinositol (GPI) and functions as a high affinity receptor for complexes of LPS and LPS binding protein (LBP). Soluble CD14, also binding to LPS, acts at physiological concentration as an LPS agonist and has, at higher concentrations, an LPS antagonizing effect in cell activation. CD14 has been shown to bind apoptotic cells.

Geminin is a 25 kDa nuclear protein, which inhibits DNA replication and is degraded during the mitotic phase of the cell cycle. Geminin controls replication by binding to the licensing factor Cdt1, and is involved in neural differentiation. In addition, Geminin directly interacts with Six3 and Hox homeodomain proteins during embryogenesis and inhibits their functions. Geminin can also promote DNA replication. Geminin has 2 roles in 2 different stages of the cell cycle: Geminin is a negative regulator of DNA replication during the “S phase” of the cell cycle. Inhibition of Geminin during the “S phase” (by RNAi) results in an additional round of replication of portions of the genome. During the “M phase” of the cell cycle (mitosis) Geminin stabilizes the replication factor Cdt1 promoting DNA replication during the next cell cycle. Moreover, inhibition of Geminin during mitosis (by RNAi) causes destabilization of Cdt1 protein and impairment of DNA replication during the next cell cycle. G

UCHL1 (PGP9.5) belongs to a gene family whose products hydrolyze small C-terminal adducts of ubiquitin to produce the ubiquitin monomer. Protein Gene Product (PGP9.5) is a neuron specific protein, structurally and immunologically distinct from neuron specific enolase. Human UCHL1 and UCHL3 have an extremely complicated knot structure for a protein, with five knot crossings. It is considered that the knot structure may increase a protein''s resistance to degradation in the proteasome. The protein, which has a molecular weight of 27 kDa was first defined by high resolution two dimetional PAGE. Standard immunohistochemical techniques have demonstrated the presence of PGP9.5 in neurons and nerve fibers at all levels of the central and peripheral nervous system, in many neurodcrine cells, in segments of the renal tubules, in spermatogonia and leydig cells of the testis, in ova and in some cells of both the pregnant and non pregnant corpus luteum. A point mutation (I93M) in UCHL1 is implicat

The Fas receptor (CD95) mediates apoptotic signaling by Fas-ligand expressed on the surface of other cells. The Fas-FasL interaction plays an important role in the immune system and lack of this system leads to autoimmunity, indicating that Fas-mediated apoptosis removes self-reactive lymphocytes. Fas signaling is also involved in immune surveillance to remove transformed cells and virus infected cells. Binding of FAS to oligimerized FasL on another cell activates apoptotic signaling through a cytoplasmic domain termed the death domain that interacts with signaling adaptors including FAF, FADD and DAX to activate the caspase proteolytic cascade. Caspase-8 and caspase-10 are first activated, to then cleave and activate downstream caspases, and a variety of cellular substrates that lead to cell death. Caspases cleave nuclear lamins, causing the nucleus to break down and lose its normal structure and another caspase substrate is DFF, inducing cleavage and degradation of the genome. Other caspase substrates are involved in cytoskeletal structure, cell cycle regulation and signaling pathways. Activation of JNK kinase, activation of Jun, and production of ceramide may also play roles in Fas-mediated apoptosis. Activation of fas-mediated apoptosis is opposed by I-FLICE and FAP. Viruses and tumors may escape immune surveillance in part through suppression of fas-mediated apoptosis using similar mechanisms.

A natural cytotoxicity receptor (NCR) NKp46 has been shown to represent a novel NK cell-specific molecule involved in human NK cell activation. The natural cytotoxicity receptors (NCRs) are a recently characterized family of Ig-like activation receptors that appear to be major triggering receptors in tumor cell recognition. The three known NCRs include NKp46 and NKp30, which are expressed on circulating NKcells, and NKp44, which is expressed only on activating NK cells. NKp46 has been implicated in NK cell-mediated lysis of several autologous tumor cells, pathogen-infected cell lines and mononuclear phagocytes infected with an intracellular bacterium. The Lysis of tumor cells by NK-cells involves recognition by NKp46 of heparan sulfate moieties of membrane heparan sulfate proteoglycans. Furthermore, NKp46 is a surface receptor involved in NK-cell cell death by apoptosis. NKp46 has two extracellular Ig-like domains followed by a ~40 residue stalk region, a type I transmembrane domain, and a short cytoplasmic tail. The extracellular Ig-like domain of NKp46 (22-255aa) is purified by FPLC gel-filtration chromatography, after refolding of the isolated inclusion bodies in a redox buffer. In addition, engagement of the antigen with the monoclonal antibody stimulates intracellular calcium levels and the synthesis of cytokines. CD59 is an NKp46 coreceptor (by physical association) together they activate cytotoxicity of human NK-cells, their engagement results in tyrosine phosphorylation of CD3-zeta chains associated with NKp46. Reduced cell surface expression of NKp46 and other NK-cell receptors is linked to the impaired NK-cell cytolytic function in viremic HIV-1 infection.

The 26S proteasome is a multicatalytic proteinase complex with a well ordered structure composed of two complexes- a 20S core and a 19S regulator. PSMD11 is a non-ATPase subunit of the 19S regulator. The 20S core is composed of four rings of 28 non-identical subunits; two rings are composed of 7 alpha subunits and two rings are composed of 7 beta subunits. The 19S regulator is composed of a base that contains six ATPase subunits and two non-ATPase subunits, and a lid that contains up to ten non-ATPase subunits. Proteasomes are spread throughout eukaryotic cells at a high concentration and cleave peptides in an ATP/ubiquitin-dependent process in a non-lysosomal pathway. An indispensable function of a modified proteasome, the immunoproteasome, is the processing of class I MHC peptides.

c-Myc is a multifunctional, nuclear phosphoprotein that plays a role in cell cycle progression, apoptosis and cellular transformation. It functions as a transcription factor that regulates transcription of specific target genes. Mutations, overexpression, rearrangement and translocation of c-Myc have been associated with a variety of hematopoietic tumors, leukemias and lymphomas, including Burkitt lymphoma. There is evidence to show that alternative translation initiations from an upstream, in-frame non-AUG (CUG) and a downstream AUG start site result in the production of two isoforms with distinct N-termini. The synthesis of non-AUG initiated protein is suppressed in Burkitt's lymphomas, suggesting its importance in the normal function of this gene.

Peptidylprolyl Isomerase C (PPIC) belongs to the peptidyl-prolyl cis-trans isomerase (PPIase) family. PPIases catalyze the cis-trans isomerization of proline imidic peptide bonds in oligopeptides and hasten the folding of proteins. Like other PPIases, PPIC binds immunosuppressant cyclosporin A.

ORF73 protein of human herpesvirus 8 is a Kaposi''s sarcoma-associated herpesvirus latent protein that is suspected of playing a critical role in modulating viral and cellular gene expression. ORF73 is linked to cellular chromatin and stays on the chromosomes during cell division. ORF73 maintains the viral genomes during cell division by tethering the viral episomes to the chromosomes. ORF73 binds directly to replication origin recognition complexes which are primarily connected with the terminal repeat region of the HHV8 genome.

AFP is normally synthesized in the liver, intestinal tract, and yolk sac of the fetus. Antibody to AFP has been shown to be useful in detecting hepatocellular carcinomas (HCC) and germ cell neoplasms, especially yolk sac tumors.

Vaspin (visceral adipose-specific SERPIN), a newly identified adipokine, which is a member of serine protease inhibitor family. Vaspin is also a unique insulin sensitizing adipocytokine in obesity. A recent publication indicates that induction of human vaspin mRNA expression in adipose tissue is regulated in a fat depot-specific manner and could be associated with parameters of obesity, insulin resistance, and glucose metabolism.

HPRT1 has a main part in the generation of purine nucleotides through the purine salvage pathway. HPRT1 primarily functions to salvage purines from degraded DNA to renewed purine synthesis. Therefore, it performs as a catalyst in the reaction between guanine and phosphoribosyl pyrophosphate to form GMP.

Interleukin-8 (IL-8) is a chemokine produced by macrophages and other cell types such as epithelial cells. It is also synthesized by endothelial cells, which store IL-8 in their storage vesicles, the Weibel-Palade bodies.
When first encountering an antigen, the primary cells to encounter it are the macrophages who phagocytosethe particle. Upon processing, they release chemokinesto signal other immune cells to come in to the site of inflammation. IL-8 is one such chemokine. It serves as a chemical signal that attracts neutrophilsat the site of inflammation, and therefore is also known as Neutrophil Chemotactic Factor.

MAFK is a member of the bZIP family and Maf subfamily. Members from Maf family of basic region/leucine zipper (bZIP) transcription factors influence transcription in a positive or negative way, depending on their protein associate and the context of the target promoter. Small Mafs act as transcriptional repressors when they dimerize among themselves. Yet, they seem to function as transcriptional activators by dimerizing with other basic-zipper proteins and employing them to specific DNA-binding sites.

CD31 is a glycoprotein expressed on endothelial cells, platelets, macrophages and Kupffer cells, granulocytes, T / NK cells, lymphocytes, megakaryocytes, fibroblasts, osteoclasts, neutrophils. In humans, the gene encoding CD31 is found on chromosome 17.
CD31 is a cluster of differentiation molecule. It is also called PECAM-1 for platelet endothelial cell adhesion molecule. It plays a key role in removing aged neutrophils from the body. Both the neutrophil and the macrophage express CD31 on their membranes, and during the testing process, these CD31 molecules bind the two cells together. If the neutrophil is healthy, it will send a signal to the macrophage, and the CD31 molecules will detach.
CD31 is also expressed in certain tumors, including epithelioid hemangioendothelioma, epithelioid sarcoma-like hemangioendothelioma, other vascular tumors, histiocytic malignancies, and plasmacytomas. It is rarely found in some sarcomas and carcinomas.

Tumor protein p53, a nuclear protein, plays an essential role in the regulation of cell cycle, specifically in the transition from G0 to G1. It is found in very low levels in normal cells, however, in a variety of transformed cell lines, it is expressed in high amounts, and believed to contribute to transformation and malignancy. p53 is a DNA-binding protein containing DNA-binding, oligomerization and transcription activation domains. It is postulated to bind as a tetramer to a p53-binding site and activate expression of downstream genes that inhibit growth and/or invasion, and thus function as a tumor suppressor. Mutants of p53 that frequently occur in a number of different human cancers fail to bind the consensus DNA binding site, and hence cause the loss of tumor suppressor activity. Alterations of the TP53 gene occur not only as somatic mutations in human malignancies, but also as germline mutations in some cancer-prone families with Li-Fraumeni syndrome.

PDIA3 is an enzyme that belongs to the endoplasmic reticulum and interacts with lectin chaperones calreticulin and calnexin to modulate folding of newly synthesized glycoproteins. PDIA3 has protein disulfide isomerase activity. Complexes of lectins and PDIA3 mediate protein folding by promoting formation of disulfide bonds in their glycoprotein substrates. PDIA3 is expressed in the lumbar spinal cord from rats submitted to peripheral lesion during neonatal period. PDIA3 interacts with thiazide-sensitive sodium-chloride cotransporter in the kidney and is induced by glucose deprivation. PDIA3 is part of the major histocompatibility complex (MHC) class I peptide-loading complex (TAP1), which is important for formation of the final antigen conformation and export from the endoplasmic reticulum to the cell surface.

PRDX1 is part of the peroxiredoxin family of antioxidant enzymes, which reduce hydrogen peroxide and alkyl hydroperoxides. PRDX1 is an important protector of red blood cells against reactive oxygen species and in tumor prevention. PRDX1 is antioxidant protective in cells, and contributes to the antiviral activity of CD8(+) T-cells. PRDX1 has a proliferative effect and is involved in cancer development or progression. Peroxiredoxin-1 is plays a role in redox regulation of the cell. Peroxiredoxin decreases peroxides with reducing equivalents provided through the thioredoxin system but not from glutaredoxin. Peroxiredoxin is involved in eliminating peroxides generated during metabolism. Peroxiredoxin participates in the signaling cascades of growth factors and TNF-alpha by regulating the intracellular concentrations of h(2)o(2).

Factor IX is a glycoprotein, which is synthesized in the liver. The domain structure of factor IX is similar to that of the other vitamin K dependent coagulation factors. The NH2-terminal region contains 12 g-carboxyglutamic acid (gla) residues, which facilitate the calcium dependent binding of factor IX to negatively charged phospholipid surfaces. Two domains which are homologous to epidermal growth factor (EGF) span the region between the NH2-terminal gla domain and the activation peptide (Ala-146 to Arg-180). Factor IX is activated by either factor XIa or the factor VIIa/tissue factor/phospholipid complex. Cleavage at site A yields the intermediate IXa, which is subsequently converted to the fully active form IXab by cleavage at site B. The NH2-terminal light chain (GLA and EGF domains) remains covalently attached to the COOH-terminal heavy chain by a disulfide bond. The serine protease catalytic triad (Ser-365, His 221, Asp-269) is located in the heavy chain. Factor IXab is the catalytic component of the “intrinsic factor Xase complex” (factor VIIIa/IXa/Ca2+/phospholipid) which proteolytically activates factor X to factor Xa.