Binding of fibrinogen to GPVI-deficient platelets and control platelets activated by (A) collagen type I and (B) CRP-XL, measured by flow cytometry using FITC-labeled fibrinogen. In GPVI-deficient platelets, there was no expression of fibrinogen binding in response to CRP-XL; collagen-induced fibrinogen binding was expressed to a decreased extent, especially at low concentrations of collagen. Fluorescence of unstimulated control platelets is defined as 1. Data shown are representative of two similar experiments.