Specificity of association of FGFR1 with α_vβ₃. ECs were incubated with 100 ng/mL FGF-2 and 10 μg/mL fibrinogen for 1 hour. Cells were then lysed and incubated with 10 μg/mL integrin antibodies as indicated. Protein A–Sepharose beads were then added and incubated further for 30 minutes. Following washing, beads were boiled in electrophoresis diluent for 5 minutes and samples were electrophoresed on 10% gels. Western blotting (WB) was performed with anti-FGFR1. The result of a representative experiment is shown.