APEX1 and cancer: Common single-nucleotide polymorphisms (SNPs) in the 8-oxoguanine glycosylase-1 (OGG1), the X-ray repair cross-complementing-1 (XRCC1), and the apurinic/apyrimidinic endonuclease-1 (APE1) genes in the BER pathway have been well studied for their influences on an individual’s sensitivity to the induction of DNA damage [17,18,19,20]; genetic variations in hOGG1, XRCC1 and APE1 could increase or decrease the risk of various cancers and noise-induced hearing loss [21,22,23,24].