Tyrosine phosphorylation of a 64-kD protein induced by NNKY5-5. (A) Gel-filtered platelets were stimulated for 10 minutes with NNKY5-5 at the indicated concentrations. The reaction was terminated with Laemmli sample buffer, and the lysates were subjected to SDS-PAGE followed by Western blotting with an anti-phosphotyrosine antibody. (B) Platelets were stimulated with 10 μg/mL NNKY5-5 for the indicated periods, and changes of protein tyrosine phosphorylation were evaluated using whole cell lysates, as described in (A).