Protein tyrosine phosphorylation induced by CD148 crosslinking. (A) Cells were incubated without (lane 1) or with (lanes 2 to 7) 10 μg of the different monoclonal antibodies for 15 minutes at 4°C followed by the addition of crosslinking rabbit antimouse Igs. Incubation was terminated after 1 minute (lanes 2, 4, and 6) and 5 minutes (lanes 3, 5, and 7). Proteins were resolved by SDS-PAGE followed by antiphosphotyrosine immunoblotting. (B) PLC-γ1 was immunoprecipitated from cells stimulated during 1 and 3 minutes and analyzed by Western blot with an antiphosphotyrosine antibody and, after stripping, with an anti–PLC-γ1.