We elected to use the DLD-1 colorectal adenocarcinoma cell line to generate the hATM KO cell line because we were unable to identify a lung cancer cell line that tolerated the loss of BRCA2 and it had previously been established that DLD-1 cells tolerate the homozygous loss of BRCA2 (6, 45). The gene discussed is BRCA2; the disease is lung cancer.