The clearest evidence that DDR activity is essential to prevent cancer onset is that cancers more frequently arise in patients carrying mutations of DDR molecules, from those regarding onco-suppressor p53, to those regarding ataxia telangiectasia mutated/ATM), ataxia telangiectasia and Rad3-related protein (ATR), BRCA-1 and so on [49]. The gene discussed is ATR; the disease is cancer.