Association of Syk with integrin IIbβ3 after the costimulation with soluble and solid-phase fibrinogen. D3-detached cells (0), the cells on fibrinogen plate incubated for 30 minutes (30), and the cells on fibrinogen plate after the additional stimulation with 1 mg/mL soluble fibrinogen for 5 minutes (30+Soluble Fg.) were lysed and immunoprecipitated with indicated antibodies. In (A) and (B), the cells were lysed in 1% Triton X-100 lysis buffer. The immunoblotting analysis for each immunoprecipitate was performed with (A) anti-Syk polyclonal antibody or (B) anti-integrin IIb MoAb. In (C) and (D), the cells were lysed in 0.05% SDS-containing buffer. The immunoblotting analysis for each immunoprecipitate was performed with (C) anti-Syk polyclonal antibody or (D) anti-integrin β3 MoAb. Results are representative of 3 experiments.