Thrombin-induced morphologic changes are not affected by staurosporine and calpeptin.

Column-purified platelets were stimulated with thrombin 1 U/mL for 60 seconds, fixed with glutaraldehyde, and stained with AlexaFluor 488 phalloidin. (A) Control, (B) thrombin, (C) staurosporine (0.3 μM) for 30 minutes, then thrombin, and (D) calpeptin (200 μg/mL) for 30 minutes, then thrombin. All platelets stimulated with thrombin show extension of filopodia and lamellipodia with F-actin polymerization. Lack of aggregation in (D) is apparent. Bar = 7 μm. Magnification × 2400.