APEX1 and cervical cancer: APE1/Ref-1 (also known as Ref-1, APE, APEX, HAP1, or hAPE) was first described in early work in which an endodeoxyribonuclease that acted on apurinic/apyrimidinic (AP) sites was purified from HeLa cervical cancer cells and human placenta [10,11,12,13].