Podoplanin binds to platelets and induces platelet activation and blood coagulation in vitro. (A-B) Mouse PRP was incubated with human podoplanin-Fc (A) or VEGFR-3-Fc (B), and Fc fusion proteins bound to CD41⁺ platelets were subsequently detected by flow cytometry, using a rabbit antihuman IgG Fcγ antibody followed by fluorescein isothiocyanate (FITC)–conjugated antirabbit antibody (red) or isotype control antibody (green). Blue: incubation without Fc fusion protein. (C) Mouse PRP was incubated with human podoplanin-Fc or VEGFR-3-Fc, before Alexa Fluor 647–conjugated human fibrinogen was added. Fibrinogen bound to CD41⁺ platelets was subsequently detected by flow cytometry. Blue: incubation with podoplanin-Fc; green: incubation with VEGFR-3-Fc; red: incubation without Fc fusion protein. (D) MCF7 cells overexpressing human podoplanin (Pdpn) or control MCF7 cells (Ctrl) were added to samples of citrate-anticoagulated mouse blood. One minute after initiation of coagulation by addition of calcium chloride, tubes were inverted and the fluidity of the blood observed.