Esophageal tumors and normal esophageal tissues (tumor free individuals) from patients were fixed with 10% formaldehyde for 2 h at 37°C, then embedded in paraffin and cut into tumor 4 µm thick sections. Antigen retrieval was performed on the tumor sections using eBioscience™ IHC Antigen Retrieval Solution (cat no. 00-4955-58, Invitrogen; Thermo Fisher Scientific, Inc.), sections were washed with PBST (Sigma-Aldrich; Merck KGaA) and subsequently incubated with mouse anti-human FGFR (1:1,000, cat no. ab10646, Abcam) or mouse anti-human VEGFR antibodies (1:1,000, cat no. ab2349, Abcam) for 12 h at 4°C. Following antibody incubation, proteins were washed with PBST three times and incubated with Alexa Fluor 488-labeled secondary antibodies (1:500; Beyotime Institute of Biotechnology, Haimen, China) for 2 h at 37°C and the specimens were visualized. A Diaminobenzidine staining system (D7679MSDS, Sigma-Aldrich; Merck KGaA) was used to detect target protein expression according to manufacturer's protocol. For histological staining, tumor sections were stained with hematoxylin and eosin and observed using a light microscope (Olympus BX51, Olympus Corporation, Tokyo, Japan) as described previously (34 (link)).