Glutathione S-transferases (GSTs) are a family of isoenzymes that detoxify electrophiles through conjugation to thiol-reduced glutathione (GSH). Thus, they are critical in protecting cells from toxins (drugs, pesticides, carcinogens) and oxidative stress. Eight isoforms of cytosolic-soluble GSTs (?, ?, ?, ?, ?, ?, ?, and ?) are identified, while only GST-?, -?, and -? are described in the central nervous system. GSTP1 (GST?) is overexpressed in early stages of carcinogenesis and can be used as a neoplastic marker in tumor tissues. GSTP1 directly inhibits TRAF2 and JNK but not NF-?B. Corresponding GSTP1 gene polymorphisms affect substrate selectivity and stability, and the oxidative milieu in dopaminergic neurons, which increases the susceptibility to Parkinson’s disease.