Effect of increasing shear rates on platelet tyrosine phosphorylations. Platelets (2.8 × 10⁸/mL) in the absence (–) or presence (+) of 2B-rVWF (0.7 μg/mL), were submitted to increasing shear rates (0 s^–1, 200 s^–1, and 4000 s^–1) for 4.5 minutes at 37°C. Lysates were prepared as described in “Materials and methods.” On the right side of the figure, platelets were either unstimulated (Resting) or stimulated by 0.5 U/mL thrombin for 2 minutes in a lumi-aggregometer. Positions of the molecular mass markers are indicated on the right side and the positions of 3 bands that are strongly phosphorylated are indicated on the left side by arrowheads. MW indicates molecular weight. Data are representative of 3 experiments.