PARP1 and cancer: DDR-related proteins, such as ataxia-telangiectasia mutated protein (ATM), breast cancer susceptibility gene (BRCA1) 6, poly [ADP-ribose] polymerase 1 (PARP-1) 7, AT-rich interaction domain 1A (ARID1A) 8, and MutL Homolog 1 (MLH)1 and MSH2 9 facilitate cancer cell survival and proliferation and the evasion of physiological cell cycle checkpoints.