APOE and esophageal squamous cell carcinoma: Seven genes were upregulated in both datasets (Fig. 6C), including TUBB, PSMB1, PSMA7, PSMA6, BID, APOE, and SPP1, while eight genes were downregulated in both datasets (Fig. 6D), including NDUFB2, VDAC2, NDUFA13, NDUFA11, GNAQ, MAP1LC3A, APPL1, and KLF2. Overall, heat maps showed that 15 genes were significantly different between ESCC and para-cancer tissues in the GSE111011 (P < 0.05, Fig. 6E) and GSE164158 (P < 0.05, Fig. 6F) datasets.