APEX1 and cancer: In particular, it was supposed recently that apoptosis of cancer cell is mediated by p53 (39,40); however, the Hep3B cell line is p53-deficient (P53−/−) with stronger Bcl-2 expression, suggesting that cells depend on the upregulation of Bcl-2 mediated by APE/Ref-1 to prevent apoptosis and further facilitate survival and development.