GSTM1 and colorectal cancer: Besides, the high activity of phase II metabolic enzymes including GST superfamily (GSTM1 and GSTT1 (40)), SULT superfamily (SULT1A1 (41)) and UGT superfamily (UGT1 and UGT2 (42)) was reported to more or less protect against dietary and/or environmental chemicals involved in the pathogenesis of colorectal cancer.