CYP2E1 and neoplasm: During the past several years, increasing evidence indicated that genes that encode metabolic enzymes can serve as tumor susceptibility genes and/or prognostic signatures, in part through their roles in activation of carcinogens; these genes include cytochrome P450 2E1 (CYP2E1) [8, 9], CYP2D6 [10], GSTP1 [11], NAT2 and GSTM1 [12].