XRCC1 and neoplasm: Expression of BER factors, like 3-alkyladenine DNA glycosylase (AAG) or N-methylpurine DNA glycosylase (MPG), 8-oxoguanine DNA glycosylase 1 (OGG1), apurinic/apyrimidinic endonuclease 1 (APE1), poly(ADP-ribose) polymerase 1 (PARP1), POL β, and now XRCC1, have been shown to influence tumor characteristics and dictate chemotherapy response [14,23,24,25,28,34,35,36,37].