Figure 2B and Figure 2C displayed the Venn diagram and heatmap of six hub genes, respectively. The expression difference between paired samples of tumor and normal group of the six genes from GEO database is demonstrated in Figure 2D. The six hub genes, namely CDKN3, BUB1, TOP2A, CEP55, KIF4A, and ECT2, were all upregulated in ESCC. The names, abbreviations, and functions for these hub genes were shown in Table 1. This evidence concerns the gene TOP2A and esophageal squamous cell carcinoma.