SIRT1 and cancer: Subsequently, two independent studies identified CCAR2 as a SIRT1-binding protein and demonstrated that the CCAR2-SIRT1 interaction inhibits SIRT1 deacetylase activity and promotes the acetylation of p53 and FOXO3 following DNA damage, resulting in the activation of p53-dependent apoptosis in several cancer cell lines7,8 (Fig. 2a).