Adherence of Syk null and Syk positive platelets to immobilized fibrinogen. Murine platelets (6 × 10⁶), either (▴) Syk null or (○) Syk positive, were added to microtiter wells coated with fibrinogen (at a range of concentrations from 1 ng to 2 μg per well). After 1 hour of incubation at room temperature, wells were washed twice and 150 μL of pNpp buffer was added for a further 1 hour at room temperature. One hundred microliters of 2 N NaOH was added and adherent platelets were quantitated in a microplate reader at 405 nm. Platelets from single mice where used to generate duplicate points for platelet adherence to each fibrinogen concentration. The graph depicts the mean ± standard error at each fibrinogen concentration, where for Syk null mice n = 10 and for Syk positive mice n = 18.