TP53 and breast carcinoma: It has been shown that circ-Foxo3 can promote MDM2-induced degradation of p53 by binding to MDM2 and p53; however, circ-Foxo3 contributes more to repression of MDM2-induced Foxo3 ubiquitination by binding to Foxo3 and thus increasing the expression of the downstream gene PUMA to induce apoptosis in breast carcinoma [50, 51].