GSTP1 and central nervous system cancer: It has been previously suggested that an increased expression of multidrug resistance (MDR) genes, DNA repair activity such as O6-methylguanine-DNA methyltransferase (MGMT), and detoxification activity such as glutathione S-transferase pi 1 (GSTP1) may be involved in causing chemoresistance to alkylating agents in glioma patients [7].