VAMP-3^−/−platelets had lower fibrinogen levels. (A) Fg levels in washed platelet extracts from WT and VAMP-3^−/− mice (3 each) were measured by western blotting. β-actin was used as loading control. (B) Quantification of Fg levels in panel A was performed using ImageQuantTL and plotted with SigmaPLot software (v13.0). (C) Comparison of protein levels by western blotting between WT and VAMP-3^−/− platelets. Washed platelet extracts (5 × 10⁷ platelets/lane) were loaded, and the indicated proteins were probed by western blotting. (D) Quantification of protein levels was performed using ImageQuantTL, and data were plotted as the ratio of VAMP-3^−/− over WT. The dashed line represents the ratio 1 of KO/WT protein levels. Statistical analyses were done using Student t test; ***P ≤ .001. Data for panels C and D are representative of platelets pooled from 2 to 3 mice in at least 2 independent experiments.