TP53 and cancer: There appears to be an inverse relationship between MSI ‘severity’ (status) and p53 mutation (Cottu et al, 1996; Breivik et al, 1997; Olschwang et al, 1997; Forster et al, 1998; Iacopetta et al, 1998), which seems paradoxical as a greater rate of p53 mutation in higher ‘mutator phenotype’ MSI-H cancers might be expected.