We also compared a panel of ESCC cell lines and non-cancer esophageal epithelial cell lines for VEGFR1 and VEGFR2 expressions, and found that the majority of cancer cell lines expressed higher VEGFR1 and VEGFR2 compared with non-cancer esophageal epithelial cells (Figure 7F). This evidence concerns the gene KDR and esophageal squamous cell carcinoma.