SIRT1 and neoplasm: Taken together, our results show that enterocyte-specific inactivation of SIRT1 reduces tumor load in the intestines of APC+/min mice by decreasing both overall tumor size and the number of larger tumors, and they suggest that SIRT1 acts as a tumor promoter by suppressing apoptosis of tumor cells in this mouse model, through mechanisms that include both activation of Wnt signaling pathway and inhibition of p53 activity.