CYP3A4 and colorectal cancer: Evidences indicating the presence of CYP3A4 and CYP3A5 mRNA transcripts in human colorectal epithelium and in cultured colorectal cancer lines have been reported (Kolars et al, 1994; Mckinnon et al, 1995; Fontana et al, 1999; Yao et al, 2000; Nakamura et al, 2002).