CHEK1 and colorectal carcinoma: Thus, 4DPG inhibited fluorouracil-resistant CRC invasion and metastasis, indicating that 4DPG may contribute to chemotherapy resistance in CRC.76, 77, 78 The results of a study on radiotherapy resistance showed that the X-ray radiation resistance associated 1 gene may promote CRC progression through ATM–Chk1/2-mediated pathways, and its low expression enhanced the phosphorylation levels of ATM, Chk1 and Chk2, which promoted tumor cell-DNA repair and led to radioresistance.79