CHEK1 and neoplasm: ATR serine/threonine, ATM (ataxia vasodilator mutation), checkpoint kinase 1 (CHK1), DNA-dependent protein kinase (DNA-PK), p38MAPK- and MAPK-activated protein kinase 2 (MK2), and other DDR inhibitors can enhance the sensitivity of chemotherapy and radiotherapy and increase the possibility of successful tumor immunotherapy (54).