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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.

DNA repair protein complementing XP-A cells, (XPA), is a member of the XPA family. XPA protein takes a part in DNA excision repair. It Inductees repair by binding to damaged sites with different affinities depending on the photoproduct and the transcriptional state of the region. Defects in XPA is the reason of xeroderma pigmentosum complementation group A (XP-A), which is infrequent human autosomal recessive disease which characterized by solar sensitivity, high predisposition for developing cancers on areas exposed to sunlight, also may cause to neurological abnormalities.

SERPINA1 is secreted and is a serine protease inhibitor which its targets include elastase, plasmin, collagenase, thrombin, leucocytic proteases, trypsin, chymotrypsin, and plasminogen activator. Defects in SERPINA1 gene can cause emphysema or liver disease. Antral SERPINA1 expression is particularly induced by H. pylori infection. lung and prostate cancers have shown a significant increase in SERPINA1 serum levels compared with healthy controls though breast cancers did not show a significant change. SERPINA1 is an endogenous inhibitor of serine proteases and inhibits the catalytic domain of human recombinant matriptase in vitro. Rise in SERPINA1 occurs as an acute phase response to tissue necrosis and inflammation. mutations in SERPINA1 and SLC11A1 genes change the balance between elastase produced by leukocytes during phagocytosis.

ACADL is a homotetramer belonging to the acyl-CoA dehydrogenase family. ACADL takes part in the catabolism of fatty acids and amino acids and is a key source of energy for the heart and skeletal muscle. Mutation in the ACADL gene results in non-ketotic hypoglycemia and hypotonia (muscle weakness).

ADFP is related with the globule surface membrane material. ADFP is a major constituent of the globule surface. Rise in mRNA levels is one of the initial indications of adipocyte differentiation. Mycobacterium leprae regulates ADFP expression to facilitate the accumulation of lipids within infected macrophages for intracellular survival. ADFP is expressed in lipid droplets of vitamin A-storing hepatic stellate cells and additionally in lipid droplets of steatotic hepatocytes. ADFP expression has a role in clear cell renal carcinoma differentiation. ADFP is a component of the lipid droplets in THP-1 cells.

Cathepsin F (CTSF) is a member of the peptidase C1 family. Cathepsins are papain family cysteine proteinases which are a main component of the lysosomal proteolytic system. The CTSF gene is ubiquitously expressed, and it maps to chromosome 11q13, close to the gene encoding cathepsin W. CTSF plays a role in normal protein catabolism. CTSF is involved in some degradative processes occurring in tumor progression since it is highly expressed in some cancer cell lines.

Myeloperoxidase is an important enzyme used by granulocytes during phagocytic lysis of foreign particles engulfed. In normal tissues and in a variety of myeloproliferative disorders myeloid cells of both neutrophilic and eosinophilic types, at all stages of maturation, exhibit strong cytoplasmic reactivity for MPO. Erythroid precursors, megakaryocytes, lymphoid cells, mast cells, and plasma cells are nonreactive. MPO is not observed in the neoplastic cells of a wide variety of epithelial tumors and sarcomas. MPO is useful in differentiating between myeloid and lymphoid leukemias.

Adenylate kinases play a role in regulating the adenine nucleotide composition within a cell by catalyzing the reversible transfer of phosphate groups among adenine nucleotides. There are 3 types of adenylate kinase isozymes, AK1, AK2, and AK3 in vertebrates. Expression of these isozymes are tissue-specific and developmentally regulated. AK2 is localized in the mitochondrial intermembrane space and is involved in apoptosis. AK2 is mutated in individuals with reticular dysgenesis.

Hexokinases phosphorylate glucose to produce glucose-6-phosphate, thus committing glucose to the glycolytic pathway. HK3 encodes hexokinase 3. Similar to hexokinases 1 and 2, this allosteric enzyme is inhibited by its product glucose-6-phosphate. Hexokinase3 lacks the hydrophobic N-terminal sequence critical for targeting to mitochondria. Hexpkinase3 may have anabolic functions, providing H6P for glycogen or lipid synthesis.

PGAM1 is part of the phosphoglycerate mutase family. PGAM1 is an essential component of glucose and 2,3-BPGA (2,3-bisphosphoglycerate) metabolism and catalyzes the reversible reaction of 3-phosphoglycerate (3-PGA) to 2-phosphoglycerate (2-PGA) in the glycolytic pathway. PGAM1 is a dimeric enzyme containing, in different tissues, different proportions of a slow-migrating muscle (MM) isozyme, a fast-migrating brain (BB) isozyme, and a hybrid form (MB). PGAM1 mutations lead to muscle phosphoglycerate mutase deficiency, a.k.a. glycogen storage disease X.

THAP Domain Containing, Apoptosis Associated Protein 11 (THAP11) is a part of the thanatos-associated protein family. THAP11 plays a role as a transcriptional repressor and interacts with HCF1 through a coiled coil domain. THAP11 which is localized to the nucleus and cytoplasm takes part in embryogenesis and pluripotency of embryonic stem cells by recruiting epigenetic modifiers.

TOP1 is an important nuclear enzyme that interconverts supercoiled DNA to the necessary topological conformations for standard DNA replication and transcription. TOP1 is the target antigen for TOP1 autoantibodies. TOP1 antibodies are a specific marker in scleroderma patients (specificity 98-100%) and are related with the existence of diffuse skin involvement and pulmonary fibrosis. In human tissues top1 enzyme is primarily synthesized as a protein with a molecular weight of 100-kDa. Most of this precursor is then proteolytically processed to a 70-kDa size, from which the TOP1 antigen has derived its name.

Paraoxonase 2 (PON2) is a member of a multigene family whose genes share 65% identity at the amino acid level, and is expressed in a variety of tissues, including the pancreas. PON2 overexpression has been shown to lower the intracellular oxidative state and reduce the cells ability to oxidize LDL. PON2 is therefore implicated in the modulation of oxidative stress.

AKR1B10 efficiently reduces aliphatic and aromatic aldehydes, and it is less active on hexoses. AKR1B10 is highly expressed in adrenal gland, small intestine, and colon, and may play an important role in liver carcinogenesis. AKR1B10 is a monomeric protein that competently catalyzes the reduction of aromatic and aliphatic aldehydes and ketones. AKR1B10 is widely expressed in numerous human tissues, small intestine, colon and adrenal gland. AKR1B10 is pathogenically involved in diabetic complications and is overexpressed in human tumors, such as liver, breast, and lung cancer, AKR1B10 is involved in the development and progression of cancer.

DLD is an L protein of the mitochondrial glycine cleavage system which is also a component of the pyruvate dehydrogenase complex, the alpha-ketoglutarate dehydrogenase complex, and the branched-chain alpha-keto acide dehydrogenase complex. DLD mutations were found in patients with E3-deficient maple syrup urine disease and lipoamide dehydrogenase deficiency.

HTATIP2 is part of the short-chain dehydrogenases/reductases (SDR) family which acts as a tumor suppressor in metabolic suppression, inhibition of angiogenesis and induces the expression of apoptosis related genes Bad and Siva. HTATIP2 cooperates with the activation domain of HIV-1 TAT and enhances its transcription by phosphorylating RNA polymerase II (Pol II). Defects in HTATIP2 are related with hepatocellular carcinomas and apoptotic resistant tumor cells, implicating a probable use for HTATIP2 in antitumor therapy.

HtrA2 also called Omi is a mammalian serine protease at high temperatures and has a chaperone activity at low temperature. The full-length HtrA2 is synthesized as a precursor protein and then targeted to the mitochondria where it is matured by the removal of N-terminal 133 residues. Mature HtrA2 consists of a putative transmembrane domain; an inhibitor of apoptosis protein (IAP)-binding motif; a single C-terminal PDZ domain that mediates protein-protein interactions. Recently, HtrA2 has known to contribute both to caspase-dependent and caspase-independent cell death.

Ubiquitin-like-conjugating enzyme ATG10 (ATG10) is a 220 amino acid protein which localizes to the cytoplasm and has a role in autophagy, specifically acting as an E2-like enzyme providing Atg recognition sites during autophagosome synthesis. ATG10 functions as an E2-like enzyme which catalyzes the conjugation of ATG12 to ATG5, which is required for autophagy. In addition, ATG10 interacts with ATG12 in human embryonic kidney cells in the presence of ATG7. ATG10 probably serves as an ATG5-recognition molecule. Furthermore, ATG10 has a role in adenovirus-mediated cell lysis.

NNMT is part of the family of transferases, especially those transferring one-carbon group methyltransferases. NNMT is mostly expressed in the liver, and a lower expression is seen in the kidney, lung, skeletal muscle, placenta and heart. NNMT catalyzes the N-methylation of nicotinamide and other pyridines to form pyridinium ions. This activity is significant for biotransformation of many drugs and xenobiotic compounds. NNMT is accountable for the enzymatic activity which uses S-adenosyl methionine as the methyl donor. NNMT expression is related with tumor stage and DFS time in hepatocellular carcinoma cases. NNMT is a good candidate as a tumor marker of various kinds of cancers. NNMT serum levels have significance in the premature detection and in the management of patients with colorectal cancer.

EMAP-II also called SCYE1 is a tumor derived cytokine that plays a role in a wide variety of activities on endothelial cells, monocytes and neutrophils. EMAP-II inhibits endothelial cell proliferation, vasculogenesis, neovessel formation, and can induce apoptosis. It is also chemotactic towards neutrophils and monocytes and induces myeloperoxidase activity from neutrophils. EMAP-II clinical value is inhibiting angiogenesis of vascular beds and suppressing the growth of primary and secondary tumors with no affect to normal tissues. SCYE1is specifically induced by apoptosis, and it is involved in the control of angiogenesis, inflammation, and wound healing. The release of this SCYE1 renders the tumor-associated vasculature sensitive to tumor necrosis factor. The precursor protein is identical to the p43 subunit, which is associated with the multi-tRNA synthetase complex, and it modulates aminoacylation activity of tRNA synthetase in normal cells. EMAP-2 plays a role in in the stimulation of inflammatory responses after proteolytic cleavage in tumor cells.

Carbonic anhydrases (CAs) are a large family of zinc metalloenzymes which catalyze the reversible hydration of carbon dioxide. These metalloenzymes participate in various biological processes, including respiration, calcification, acid-base balance, bone resorption, and the formation of aqueous humor, cerebrospinal fluid, saliva, and gastric acid. The metalloenzymes exhibit extensive diversity in tissue distribution and in their subcellular localization. Carbonic Anhydrase XI (CA11) is probably a secreted protein, nevertheless, drastic changes at active site residues completely conserved in CA isozymes with catalytic activity, make it unlikely that CA11 has carbonic anhydrase activity. CA11 shares properties in common with 2 other acatalytic CA isoforms, CA VIII and CA X. CA11 is amply expressed in the brain, and may have a general role in the central nervous system.

Thymine-DNA glycosylase (TDG) is a member of the TDG/mug DNA glycosylase family.
TDG is a nuclear protein that fixes G/T mismatches to G/C pairs by hydrolyzing the carbon-nitrogen bond between the sugar-phosphate backbone of the DNA and the mispaired thymin. In addition, TDG removes uracil and 5-bromouracil from mispairings with guanine. The TDG enzyme has an essential role in cellular defense against genetic mutation triggered by the spontaneous deamination of 5-methylcytosine and cytosine.

PGAM1 is part of the phosphoglycerate mutase family. PGAM1 is an essential component of glucose and 2,3-BPGA (2,3-bisphosphoglycerate) metabolism and catalyzes the reversible reaction of 3-phosphoglycerate (3-PGA) to 2-phosphoglycerate (2-PGA) in the glycolytic pathway. PGAM1 is a dimeric enzyme containing, in different tissues, different proportions of a slow-migrating muscle (MM) isozyme, a fast-migrating brain (BB) isozyme, and a hybrid form (MB). PGAM1 mutations lead to muscle phosphoglycerate mutase deficiency, a.k.a. glycogen storage disease X.