KDR and esophageal squamous cell carcinoma: Two ESCC cell lines with relative high expression of VEGFR1 and VEGFR2 were treated with VEGFR1 and VEGFR2 antibodies, and the results showed that proliferation of the treated cancer cells was significantly inhibited by the antibody treatments (Figure 7G), which suggests that ESCC cells are also valid targets for VEGFR1/VEGFR2 antibody therapies.