The perturbed cell cycle regulation pathway in ESCC mainly exhibited genetic alterations in the G1/S transition control, including mutations or deletions of TP53, RB1, CDKN2A, CHEK1, and CHEK2, and amplifications of CDK4, CCND1, CDK6, and MDM2 (Song et al., 2014). This evidence concerns the gene CDKN2A and esophageal squamous cell carcinoma.