APEX1 and neoplasm: In several cancers (including lung, colorectal, cervical, prostate, bladder, gastric, hepatic, glioblastoma, osteosarcoma, head and neck, ovarian, and breast) high APE1 expression or aberrant cytoplasmic distribution (Table 1) have been associated with tumour aggressiveness, poor prognosis or increased resistance to DNA-damaging agents [55,56].