KDR and esophageal squamous cell carcinoma: To test the efficacy of anlotinib, raltitrexed and the combination of drugs on the proliferation of ESCC cells, we co-cultured different concentrations of anlotinib and raltitrexed with KYSE-30 and TE-1 cell lines which expressed the vascular endothelial growth factor receptor, VEGFR-2 [21–23].