Glutathione S-transferase P (GSTP1) is an enzyme that contains 1 GST C-terminal domain, 1 GST N-terminal domain. GSTP1 belongs to the GST superfamily, the GSTs are a family of enzymes that play an important role in detoxification by catalyzing the conjugation of many hydrophobic and electrophilic compounds with reduced glutathione. Based on their biochemical, immunologic, and structural properties, the soluble GSTs are categorized into 4 main classes: alpha, mu, pi, and theta. The glutathione S-transferase pi gene (GSTP1) is a polymorphic gene encoding active, functionally different GSTP1 variant proteins. Besides, it regulates negatively CDK5 activity via p25/p35 translocation to prevent neurodegeneration. It thought to function in xenobiotic metabolism and play a role in susceptibility to cancer, and other diseases.