Influence of TPO and thrombin on Btk phosphorylation.

Platelets were treated with 50 μg/mL collagen, (A) 100 ng/mL TPO, (B) 1 unit/mL thrombin for 0 to 10 minutes, or (C) 1 unit/mL thrombin for 0 to 5 minutes, as indicated. (A,B) Btk or (C) Tec was purified from soluble extracts by immunoprecipitation as described above and immunoblotted with either 4G10 antibody (top panels) or anti-Btk or anti-Tec antibody (bottom panels).