The mutation frequency of the cancer genes TP53, CDKN2A, CDKN1A, CCND1, and NFEL2 was significantly higher than that of normal genes Slc7a11 and CCNA2 (p21Cip1) and their co-occurrence in cancer patients is well established (Table S2 and ref. 18). This evidence concerns the gene CDKN1A and cancer.