CDK1 and esophageal squamous cell carcinoma: The result indicated that there was obvious difference in mRNA expression of CDK1 between cancer tissues and normal esophageal tissues (Fig. 2A–D), and the expression of CDK1 was obviously increased in ESCC tissues (5.261 ± 0.703 vs. 2.229 ± 1.161, P < 0.0001; Fig. 2C).