MSH2 and neoplasm: A significantly higher proportion of p53-positive cells with high to moderate nuclear staining was observed in ethanol-treated induced Aldh1b1−/− Msh2-LS (non-tumour bearing) colonic mucosal epithelia (47.5%) compared with that in water-treated induced Aldh1b1−/− Msh2-LS colonic epithelia (3.3%) (P<0.0001, unpaired two-tailed Student's t-test) (Fig. 2I,J, Fig. 3J).