APEX1 and breast cancer: The abasic (AP) site aroused by DNA single-strand breaks can be recognized and excised by APE1. The association between APE1 rs1760944 (−656T>G) and rs1130409 (Asp148Glu) polymorphisms and the risk of renal cell carcinoma and breast cancer have been indicated in several case-control studies [3, 4].