Confocal photomicrographs of annexin V binding with fibrinogen-adherent platelets.

Following adherence to fibrinogen-coated coverslips, SLP-76^+/− (A-C) or SLP-76^−/− (D-F) platelets were stimulated with thrombin (0.5 U/mL; A,D), collagen (50 μg/mL; B,E), or thrombin plus collagen (C,F). Adherent platelets and platelet aggregates were identified by staining with FITC anti-CD49b (green fluorescence) and annexin V binding was detected by staining with PE-conjugated annexin V (red fluorescence). Yellow fluorescence indicates costaining for both CD49b and annexin V binding. Original magnification × 200.