The role of Lyn in GPIb-IX–mediated elevation of platelet cGMP. Washed wild-type or Lyn^−/− platelets were stimulated with botrocetin alone or botrocetin (1.2 μg/mL) and VWF (10 μg/mL) in an aggregometer for 5 minutes. The cGMP levels (mean ± SD) in platelets were measured as described in “VWF-induced platelet cGMP elevation.” Data were obtained from 3 tests.