The results showed that the mRNA expression levels of hub genes (PBK, KIF2C, NUF2, KIF20A, RAD51AP1 and DEPDC1) in tumor samples (EAC, ESCC) were significantly higher than in normal samples (P < 0.05) (Fig. 6A). This evidence concerns the gene RAD51AP1 and esophageal squamous cell carcinoma.