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Peroxisome proliferators are non-genotoxic carcinogens which are purported to exert their effect on cells through their interaction with members of the nuclear hormone receptor family termed peroxisome proliferators activated receptors (PPARs). Nuclear hormone receptors are ligand-dependent intracellular proteins that stimulate transcription of specific genes by binding to specific DNA sequences following activation by the appropriate ligand. Studies indicate that PPARs are activated by peroxisome proliferators such as clofibric acid, nafenopin, and WY-14,643, as well as by some fatty acids.

The peroxisome proliferator activated receptors (PPARs) are ligandactivated transcription factors within the nuclear receptor superfamily, which play important roles in adipogenesis, glucose homeostasis andinflammation. Three different isotypes can be distinguished; alpha, beta and gamma. PPARg, is mainly expressed in adipose tissue and to lesser extent in colon, the immune system and the retina. Whereas PPARg operates in the catabolism of fatty acids in the liver, PPARg influences the storage of fatty acids in the adipose tissue and plays a role in adipocyte differentiation. PPARg binds to DNA as a heterodimer with retinoid X receptor (RXR), activating expression of target genes after binding ligand.

Peroxisome proliferators are non-genotoxic carcinogens which are purported to exert their effect on cells through their interaction with members of the nuclear hormone receptor family termed peroxisome proliferators activated receptors (PPARs). Nuclear hormone receptors are ligand-dependent intracellular proteins that stimulate transcription of specific genes by binding to specific DNA sequences following activation by the appropriate ligand. Studies indicate that PPARs are activated by peroxisome proliferators such as clofibric acid, nafenopin, and WY-14,643, as well as by some fatty acids.

PPARGC1A is transcriptional coactivator for steroid receptors and nuclear receptors which increases the transcriptional activity of PPARG and thyroid hormone receptor on the uncoupling protein promoter. PPARGC1A regulates main mitochondrial genes that contribute to the program of adaptive thermogenesis and plays an important role in metabolic reprogramming in response to dietary availability through coordination of the expression of many genes participate in glucose and fatty acid metabolism. PPARGC1A induces the expression of PERM1 in the skeletal muscle and takes part in the integration of the circadian rhythms and energy metabolism.

The fasting-induced adipose factor (FIAF, ANGPTL4, PGAR, HFARP) was identified as an adipocytokine up-regulated by fasting, by peroxisome proliferator-activated receptor agonists, and by hypoxia. At the protein level, in human and mouse blood plasma, FIAF was found to be present both as a native protein and in a truncated form. Differentiation of mouse 3T3-L1 adipocytes was associated with the production of truncated FIAF, whereas in human white adipose tissue and SGBS adipocytes, only the native FIAF could be detected. Interestingly, the truncated FIAF was produced by human liver.
Experimental data suggest that FIAF is mainly presented in human blood plasma in a truncated form (FIAF-S2), whose level is increased by fenofibrate treatment. Levels of both truncated and native FIAF showed marked inter individual variation but were not associated with body mass index and were not influenced by prolonged semistarvation.

FIAF (fasting-induced adipose factor) a.k.a ANGPTL4 or PGAR or HFARP is an adipocytokine up-regulated by fasting, by peroxisome proliferator-activated receptor agonists, and by hypoxia. ANGPTL4 is found in human and mouse blood plasma both as a native protein and in a truncated form. In human white adipose tissue and SGBS adipocytes, only the native form of ANGPTL4 could be detected, whereas in mice the differentiation of mouse 3T3-L1 adipocytes is associated with the production of truncated ANGPTL4. However, the truncated ANGPTL4 is produced by human liver. In human blood plasma FIAF is mainly presented in a truncated form (FIAF-S2), whose levels treatment increases (as shown by experimental data). There is an inter individual variation in ANGPTL4 levels of both the truncated and the native form, however those levels were not influenced by prolonged semistarvation and are not associated with body mass index.

PMSG Hormone is a well know used hormone together with progestogen to increase ovulation just before to artificial insemination. PMSG hormone is a placental glycoprotein produced from the serum of pregnant mares. PMSG comprises of an alfa subunit and a beta subunit. PMSG hormone is secreted from endometrial cups within the pregnant mare uterus aging from 40 to 130 days into their maturation, and once extracted, it can been used to promote artificially estrus in female animals. These assemblies produce PMSG hormone to induce mare's ovarian and repsouctive structures. PMSG can induce the growth of follicles by ovaries and results in ovulatation. PMSG hormone has an about a 4 day half-life of bioactivity in species other than horses. The extended biological activity can cause ovarian stimulation and ovulation. However, PMSG use alone often causes cystic ovarian disease because of the unrestrained ovarian stimulation and due to the sugar molecules which decrease clearance of the hormone. PMSG is more likely to be used than other pituitary hormones due to the extended circulatory half-life. PMSG solely exhibits luteinizing hormone like activity, however in other animal classes it has FSH & LH like activity.

Acyl-CoA synthetase family member 2, also known as ACSF2 is a member of the ATP-dependent AMP-binding enzyme family. Acyl-CoA synthetases are a family of enzymes which catalyze the thioesterification of fatty acids with coenzymeA to form activated intermediates, which play a basic part in lipid metabolism as well as homeostasis of lipid-related processes. ACSF2 is required for the complex of lipid synthesis, energy production via beta-oxidation, protein acylation and fatty-acid dependent transcriptional regulation. Moreover, ACSF2 is required for fatty acid import into cells by the process of vectorial acylation.

PDRG1 is a 133 amino acid protein that localizes to the cytoplasm and belongs to the prefoldin subunit beta family. PDRG1 is expressed primarily in normal testicular tissue, it is functionally induced by ultraviolet light and is thought to have a role in chaperone-mediated protein folding, possibly having a role in cellular degradation. PDRG1 is linked to Creutzfeldt-Jakob disease, amyotrophic lateral sclerosis, spinal muscular atrophy, ring chromosome 20 epilepsy syndrome and Alagille syndrome.

Acyl-CoA synthetase family member 2, also known as ACSF2 is a member of the ATP-dependent AMP-binding enzyme family. Acyl-CoA synthetases are a family of enzymes which catalyze the thioesterification of fatty acids with coenzymeA to form activated intermediates, which play a basic part in lipid metabolism as well as homeostasis of lipid-related processes. ACSF2 is required for the complex of lipid synthesis, energy production via beta-oxidation, protein acylation and fatty-acid dependent transcriptional regulation. Moreover, ACSF2 is required for fatty acid import into cells by the process of vectorial acylation.

Prostaglandin Reductase 2 (PTGR2) is a member of the medium-chain dehydrogenase/reductase superfamily. PTGR2 is an enzyme involved in the metabolism of prostaglandins. PTGR2 catalyzes an NADPH-dependent reduction of the conjugated alpha, beta-unsaturated double bond of 15-keto-PGE(2), which is a fundamental step in terminal inactivation of prostaglandins and suppression of PPARgamma-mediated adipocyte differentiation. PTGR2 may also be involved in controlling activation of the peroxisome proliferator-activated receptor.

Pregnancy Specific Beta-1-Glycoprotein 1 (PSG1) is a member of a subgroup of transcription factors which are phosphorylated upon binding to promoter sequences. PSGs belong to the carcinoembryonic antigen (CEA) family and function as early biochemical markers of syncytiotrophoblast formation. Furthermore, PSG1 is assumed to mediate placental vascular morphogenesis by enhancing VEGF-A production and endothelial tube formation. PSG1 is a major product of the syncytiotrophoblast, reaching concentrations of 100- 290 mg/l at term in the serum of pregnant women.

Progastricsin-C (PGC) is an aspartic proteinase which is synthesized in the gastric mucosa as inactive precursors. PGC is a part of the peptidase family A1 and contains a prosegment which is responsible for stabilizing the inactive form and preventing the entrance of the substrate to the active site. PGC is used as a biomarker for various gastric diseases including Helicobacter pylori related gastritis. PGC is also hydrolyzes various proteins.

Placental Growth Factor (PLGF) which is a member of the VEGF sub-family, is a growth factor active in angiogenesis, and endothelial cell growth, stimulating their proliferation and migration. PLGFmainly plays a role in trophoblast growth and differentiation and binds to receptor vegfr-1/flt1.

Prostaglandin Reductase 1 (PTGR1) is a member of the NADP-dependent oxidoreductase L4BD family. PTGR1 catalyzes the conversion of leukotriene B4 into its biologically less active metabolite, 12-oxo-leukotriene B4, thus being a primary step of metabolic inactivation of leukotriene B4. PTGR1 is highly expressed in the kidney, liver, and intestine but not in leukocytes.

Phosphoglycolate phosphatase (PGP) is discovered in all tissues including red cells, lymphocytes and cultured fibroblasts (at protein level). PGP is most active in skeletal muscle and cardiac muscle. The catalytic activity of PGP is 2-phosphoglycolate + H2O = glycolate + phosphate. Diseases associated with PGP include tardive dyskinesia and polycystic kidney disease.

Phosphoglycerate mutase 2 (PGAM2) is a member of the phosphoglycerate mutase family. PGAM is a dimeric enzyme which contains in separate tissues, different proportions of a slow-migrating muscle (MM) isozyme, a fast-migrating brain (BB) isozyme, and a hybrid form (MB). PGAM (Phosphoglycerate mutase) catalyzes the reversible reaction of 3-phosphoglycerate (3-PGA) to 2-phosphoglycerate (2-PGA) in the glycolytic pathway. PGAM2 gene mutations cause muscle phosphoglycerate mutase efficiency, otherwise known as glycogen storage disease X.

L-Asparaginase is an enzyme that depletes L-Asparagine "an important nutrient for cancer cells" resulting in cancer/tumor cell starvation. L-asparaginase is an anti-tumor agent derived from E.coli.,which can inhibit the growth of malignant cells. It is used mainly for the induction of remission in acute lymphoblastic leukaemia. Because of the lymph node origin of malignant B cells in Multiple Myeloma, L-Asparagine is an essential amino acid for their cell metabolism, and, consequently, L-Asparaginase may be of value in managing the disease.
The rationale behind asparaginase is that it takes advantage of the fact that ALL cellsare unable to synthesize the non-essential amino acidasparaginewhereas normal cells are able to make their own asparagine. These leukemic cells depend on circulating asparagine. Asparaginase however catalyzes the conversion of L-asparagine to aspartic acidand ammonia. This deprives the leukemic cell of circulating asparagine.

PRKAG1 is a regulatory subunit of the AMP-activated protein kinase (AMPK). AMPK is a heterotrimer comprised of an alpha catalytic subunit, and non-catalytic beta and gamma subunits. AMPK is a vital energy-sensing enzyme which supervises cellular energy status. PRKAG1 is one of the gamma regulatory subunits of AMPK. Alternatively spliced transcript variants encoding dissimilar isoforms were found.

PLGF is a growth factor active in angiogenesis, and endothelial cell growth, stimulating their proliferation and migration. It binds to receptor vegfr-1/flt1.
PLGF-2 binds neuropilin-1 and 2 in a dependent way.

PGK1 is an X-linked enzyme that has a major role in the glycolytic pathway. PGK1 is a glycolytic enzyme which catalyzes the conversion of 1,3-diphosphoglycerate to 3-phosphoglycerate, generating an ATP molecule. PGK1 may also act as a cofactor for polymerase alpha. Defects in the PGK1 gene are usually associated with chronic hemolytic anemia, though it can be accompanied by either mental retardation or muscular disease (rhabdomyolysis). Overexpression of PGK1 and its signalling targets are possibly an expression-pathway in diffuse primary gastric carcinomas promoting peritoneal dissemination. It was shown that PGK1 is differentially expressed in the dorsolateral prefrontal cortex from patients with schizophrenia.

Pregnancy Specific Beta-1-Glycoprotein 1 (PSG1) is a member of a subgroup of transcription factors which are phosphorylated upon binding to promoter sequences. PSGs belong to the carcinoembryonic antigen (CEA) family and function as early biochemical markers of syncytiotrophoblast formation. Furthermore, PSG1 is assumed to mediate placental vascular morphogenesis by enhancing VEGF-A production and endothelial tube formation. PSG1 is a major product of the syncytiotrophoblast, reaching concentrations of 100- 290 mg/l at term in the serum of pregnant women.

PA2G4 belongs to the peptidase M24C family and functions as an RNA-binding protein involved in cellular proliferation and differentiation processes. PA2G4 is a component of pre-ribosomal ribonucleoprotein complexes, participating in ribosome assembly and regulating the later steps of rRNA processing. Also, PA2G4 interacts with ErbB-3 and may function as a modulator of the ErbB-3 mediated signal transduction pathway by regulating the effects of Neuregulin-1. Furthermore, PA2G4 is a transcriptional co-repressor of androgen receptor-regulated genes and other cell cycle regulatory genes through its interactions with histone deacetylases. PA2G4 is implicated in growth inhibition and the induction of differentiation of human cancer cells. In addition, PA2G4 mediates cap-independent translation of specific viral IRESs (internal ribosomal entry site). PA2G4 associates with 28S, 18S and 5.8S mature rRNAs, several rRNA precursors and probably U3 small nucleolar RNA.

Poly (ADP-Ribose) Polymerase 2 (PARP2) contains a catalytic domain which is homologous to that of poly (ADP-ribosyl) transferase but lacks an N-terminal DNA binding domain which activates the C-terminal catalytic domain of poly (ADP-ribosyl) transferase. PARP2 is capable of catalyzing a poly (ADP-ribosyl)ation reaction. The basic residues within the N-terminal area of this protein can bear potential DNA-binding properties, and can be engaged in the nuclear and/or nucleolar targeting of the protein. There has been found two alternatively spliced transcript variants encoding distinct isoforms.