Spreading but not adhesion of mouse platelets on laminin is dependent on Syk and PLCγ2. (A) Washed murine platelets (3 × 10⁷/mL) from control, Syk-deficient (Syk^-/-), or PLCγ2-deficient (PLCγ2^-/-) mice were pretreated with the α_IIbβ₃ blocker, lotrafiban (10 μM), before seeding on laminin-coated coverslips as described in Figure 1. Real-time imaging was performed using videomicroscopy with DIC optics. (B) (i) The number of adherent platelets was counted. The graph illustrates the mean number of percent wild-type adhesion ± SEM per image from at least 4 different images from 2 separate experiments. (ii) Total surface coverage of adherent platelets on laminin was measured using NIH image software. The graph illustrates the percent wild-type surface coverage ± SEM per image from at least 4 different images from 2 separate experiments. (iii) Number of filopodia-like projections in adherent platelets was counted. The graph illustrates the mean number of filopodia-like projection ± SEM per adherent platelet of at least 240 platelets from 2 separate experiments.