CHEK1 and non-small cell lung carcinoma: ATR can be activated by recruitment to its partner protein ATRIP, binding to topoisomerase (DNA) II binding protein 1 (TopBP1) and claspin, phosphorylated Chk1 (34), activated Chk1 phosphorylated WEE1, leading to cell cycle arrest and DNA repair (35), resulting in radioresistance of NSCLC (36, 37).