The serine/threonine kinase ataxia telangiectasia mutated (ATM) is a key protein kinase that regulates multiple DDR processes including DNA repair through the NHEJ and HR pathways.3 While both the NHEJ and HR pathways are involved in cancer resistance to genotoxic therapies, the HR repair pathway is particularly critical in highly proliferative cancer cells. The gene discussed is ATM; the disease is cancer.