TP53 and nasopharyngeal carcinoma: It is well known that chk2 regulates p53-related pathways such as p21-mediated pathway, and p21 is involved in the radioresistance of various tumor types, including some of those occurring in the lungs, the brain, the prostate, the cervix, the esophagus, and the large intestine, as well as in nasopharyngeal carcinoma.