The primary antibodies used here included rat anti-mouse CD31 antibody (Biolegend, CA, USA), mouse anti-human CD31 antibody and rabbit anti-human PDGFRβ antibody (Abcam CA, USA). The secondary antibodies were goat anti-rat IgG (DyLight 550), donkey anti-rabbit IgG antibody (DyLight 488 or DyLight 550), and goat anti-mouse IgG (DyLight 550) (Abcam, CA, USA). Tumor tissues derived from patients or mice were frozen, sectioned and fixed with 2 % formaldehyde for 4 min. Subsequently, the tissues were incubated with primary antibody at 37°C for 1.5 h followed by incubation with the corresponding secondary antibody at 37°C for 0.5 h. In addition, the tissues were washed with PBS 4 times prior to incubation with either primary antibody or secondary antibody. The nuclei of cells were visualized using DAPI staining.
To localize the recombinant proteins on PDGFRβ-expressing cells in tumors, FAM-labeled proteins were intravenously injected into mice bearing LS174T tumor xenografts. Subsequently, the tumor xenografts were removed at 5, 30, and 60 min post-injection and frozen and sectioned followed by staining with anti-PDGFRβ antibody or anti-CD31 antibody.
To localize the recombinant proteins on PDGFRβ-expressing cells in tumors, FAM-labeled proteins were intravenously injected into mice bearing LS174T tumor xenografts. Subsequently, the tumor xenografts were removed at 5, 30, and 60 min post-injection and frozen and sectioned followed by staining with anti-PDGFRβ antibody or anti-CD31 antibody.