Glutathione-S-transferase gene polymorphisms in colorectal cancer patients: interaction between GSTM1 and GSTM3 allele variants as a risk-modulating factor. Loktionov A, Watson MA, Gunter M, Stebbings WS, Speakman CT, Bingham SA Carcinogenesis. Jun 2001 (DOI : 10.1093/carcin/22.7.1053)