FOXO3 and cancer: In cancer cells in which the activity of sirtuins (i.e. SIRT4, SIRT5, SIRT6, and SIRT7) is upregulated, combined treatment with sirtuin inhibitors—such as sirtinol, salermide or EX527—and doxorubicin or epirubicin helps cells to overcome chemoresistance by mediating FOXO3a deacetylation and inhibition [114].