MYC and cancer: SIRT1 activates c-Myc by deacetylation via positive feedback.232 Moreover, SIRT1 deacetylates and activates FOXO3, which contributes to oxidative stress resistance by upregulating antioxidant proteins.196,234,235 SIRT1 is also involved in the promotion of cancer cell proliferation, angiogenesis, and metastasis through the activation of the MAP kinase pathway by deacetylation.234,235 All these data corroborate the oncogenic role of SIRT1, which strongly depends on the NAD+ pool and NAMPT activity.