Effects of SFK inhibitor and Lyn knockout on platelet spreading on immobilized VWF. Microtiter chamber slides were coated with 30 μg/mL of VWF. Washed wild-type mouse platelets were preincubated with DMSO or PP2 (10 μM) for 5 minutes. Wild-type or Lyn^−/− platelets were allowed to adhere and spread on VWF for 90 minutes in the presence of (A) botrocetin (1 μg/mL) or (B) ADP (10 μM). Adherent platelets were stained with fluorescein-labeled phalloidin and photographed under a fluorescence microscope. Shown are representative pictures from one of 3 experiments with similar results. The bars in the graph represent the average surface area (± SD) of individual platelets. ###P < .001, compared with WT platelets. ***P < .001, compared with DMSO-treated WT platelets. The number of platelets analyzed for each group is indicated above the bars.