Colocalization of α_vβ₃ and FGFR1 using coimmunoprecipitation. ECs or HFFs were exposed to various conditions, as described. After 1 hour, cells were washed with PBS, lysed with lysis buffer, and incubated with 5 μg/mL of either 7E3 (A-D) or anti-FGFR1 (E-F). Protein A–Sepharose beads were then added. Following washing, the beads were incubated with diluent and electrophoresed on 10% gels. Western blotting was performed with anti-FGFR1 (A-D) or with 7E3 (E-F). In panels A, C, and E: lane 1, medium alone; lane 2, 100 ng/mL FGF-1; lane 3, 100 ng/mL FGF-2; lane 4, 10 μg/mL fibrinogen; lane 5, 10 ng/mL IL-1β; lane 6, 100 ng/mL FGF-1 plus 10 μg/mL fibrinogen; lane 7, 10 ng/mL IL-1α plus 10 μg/mL fibrinogen; lane 8, 100 ng/mL FGF-2 plus 10 μg/mL fibrinogen. Panels B, D, and F are supernatants after centrifugation of protein A–Sepharose: lane 1, medium alone; lane 2, 10 μg/mL fibrinogen; lane 3, 100 ng/mL FGF-2; lane 4, 100 ng/mL FGF-2 plus 10 μg/mL fibrinogen. Arrows indicate the location of FGFR1 (Mr ∼100 kDa) in panels A-D; the arrows indicate the location of α_vβ₃ in panels E-F (Mr ∼110 kDa).