APEX1 and cancer: Specifically, we will discuss targeting the DNA base excision repair (BER) enzyme apurinic/apyrimidinic endonuclease 1/redox-factor-1 (APE1/Ref-1), a multifunctional protein involved in both DNA repair and redox signaling, whose expression is altered in numerous cancers including prostate, colon, ovarian, cervical, and germ cell tumors [17].