ATR and cancer: Other highly mutated HR-related genes, including RAD51B (mutation frequency in patients, 6.1%), ATR (6.1%), ATM (6.1%), PALB2 (6.1%), and BRIP1 (4.9%) (Fig. 1, B), have been reported to be capable of affecting the sensitivity of various cancer cells to PARPis (22, 23, 24, 25, 26, 27).