Figure 4.

Deficiency of SLP-76 impairs αIIbβ3-dependent tyrosine phosphorylation and shape change in platelets. (A) Washed SLP-76^−/− or SLP-76^+/− platelets were incubated on coverslips coated with 100 μg/ml fibrinogen. Cells were permeabilized, fixed, and then stained for phosphotyrosine (green) and F-actin (red). The bar in the lower right corner corresponds to 10 μm. (B and C) Washed SLP-76^−/− or SLP-76^+/− platelets were placed on fibrinogen-coated coverslips and left unstimulated (B) or stimulated with 30 μg/ml collagen (C). Cells were then examined by SEM. Each image is ×5,000. Results shown are typical of three separate experiments.