The glutathione S-transferases (GSTs) represent a major group of detoxification enzymes that catalyze the nucleophilic addition of the tripeptide glutathione (GSH) to many xenobiotics and endogenous electrophiles. 1 The level of expression of GSTs is a crucial factor in determining the susceptibility to cancer chemotherapy. Three classes of GST isozymes, Alpha (A), Mu (M) and Pi (P) are often found over-expressed in drug-resistant tumor or tumor cell lines. 1,2 ...