SIRT1 and intraepithelial neoplasia: For instance in some lesions with high grade intraepithelial neoplasia and KRAS mutation that displayed high c-MYC and SIRT1 expression (Figure 5a, b), no nuclear beta-catenin was detected (Figure 5c), whereas other lesions with equally high c-MYC and SIRT1 levels were positive for nuclear beta-catenin (data not shown).