Consistently, we found that the expression of SOX9, at both protein and mRNA level, was significantly upregulated in all 11 tested ESCC cell lines as compared to the two normal esophageal epithelial cells (NEECs), and in the eight human ESCC samples as compared to the matched adjacent non-tumor tissues (Figure 1B–1D and Supplementary Figure 1A–1C), suggesting that SOX9 is overexpressed in ESCC. This evidence concerns the gene SOX9 and esophageal squamous cell carcinoma.