ATM and hereditary nonpolyposis colon cancer: The ataxia telangiectasia mutated (ATM) gene encodes a high‐molecular weight protein kinase which has been proposed to play a pivotal role in triggering appropriate cellular response to genome damage.19 Kim et al14 investigated the radio‐sensitivity of 3 hereditary Non‐Polyposis Colorectal Cancer (HNPCC) cell lines (HCT‐116, LoVo and RKO).