Therefore, genetic ablation or pharmacological inhibition of Parp-1 enhances the Sirt1 activity through restoring the NAD+ content, providing a protection benefit for various tissues, including the liver, muscle and brown adipose tissue.630,631 NADP+ has been demonstrated as an endogenous inhibitor of PARPs, which extend the therapeutic effect of PARP inhibitors on cancers with higher levels of NADP+. This evidence concerns the gene SIRT1 and cancer.