SIRT1 and cancer: SIRT1 was later found to deacetylate and regulate several other proteins that share similar roles in cellular stress responses (e.g. Ku70, p73, FoxO3a, FoxO4 and E2F1[13]–[17]), while small-molecule inhibitors of SIRT1 were shown to exhibit antitumor activity, suggesting that pharmacological inhibition of SIRT1 could be therapeutically beneficial in a subset of human cancers [18]–[23].