Rat anti mouse cd31 and cd11b

The excised tumor and organs were snap-frozen in liquid nitrogen, cryosectioned at 10 μm, fixed with 4% paraformaldehyde for 10 min at room temperature (RT), and immunostained with anti-fluorescein rabbit immunoglobulin G (IgG) fragment (Thermo Fisher Scientific, Waltham, MA, USA), rat anti-mouse CD31 and CD11b (BD Biosciences, Franklin Lakes, NJ, USA) as primary antibodies, and Alexa Fluor 488 goat anti-rabbit IgG and Alexa Fluor 647 goat anti-rat IgG (Thermo Fisher Scientific, Waltham, MA, USA) as secondary antibodies. The nuclei of cells were stained with 4′,6-diamidino-2-phenylindole (DAPI; 5 μL/mL, 10 min). Images of the tissue sections were taken with confocal microscopy (Olympus FV1200MPE, Hamburg, Germany).