It is clear that in the top ten genes in PPI network of CESC, ESCC, and LUSC, nine of them (BUB1, BUB1B, CCNA2, CCNB1, CCNB2, CDC20, CDC6, CDK1, and MAD2L1) are the same. Here, CDK1 is linked to esophageal squamous cell carcinoma.