GSTP1 is a polymorphic gene encoding active， functionally different GSTP1 variant proteins that are believed to function in xenobiotic metabolism and have a part in susceptibility to cancer， and other diseases. GSTP1 is a glutathione S-transferase belonging to the pi class. GST family enzymes play a significant role in detoxification by catalyzing the conjugation of many hydrophobic and electrophilic compounds with reduced glutathione. Based upon the biochemical， immunologic and structural properties of the soluble GSTs they are grouped into 4 main classes: alpha， mu， pi， and theta. The GSTP1 enzyme acts by catalyzing the reaction of glutathione with an acceptor molecule to form a Sulfur-substituted glutathione. The reactions employing glutathione contribute the transformation of a broad range of electrophiles， including reactive products of lipid， protein， carcinogens， therapeutic drugs， environmental toxins， and products of oxidative stress.
The GSTP1 inactivation through CpG hypermethylation is frequent in pituitary adenomas and may be a factor in aggressive pituitary tumor behavior. GSTP1 is may be a transcriptional target of the p53 tumor suppressor gene. Single-nucleotide polymorphism in GSTP1 is linked to modified protein binding， which influence GSTP1’s contribution to carcinogen and drug metabolism， and possibly disease pathogenesis and/or drug response. GST-pi might have central roles in proliferation of androgen-independent human prostate cancer cells.
