Formation of filopodia in WASp-deficient platelets. The presence of filopodia on control and platelets stimulated with CRP (5 μg/mL), thrombin (1 U/mL), and collagen (30 μg/mL) from WAS and control donors was assessed by scanning electron microscopy (SEM). Original magnification × 5,200. Results are representative of 6 independently analyzed fields.