Sustained platelet activation is impaired in mice overexpressing VWF/p.V1316M. αIIbβ3 integrin activation measured by flow cytometry with JON/A-PE antibody (selectively binds to the activated form of the receptor⁵¹ ). JON/A-PE was added with the agonist (PAR4p, 200 μM) (A) or 10 minutes after the agonist (B-C). The mean fluorescence intensity measured in stimulated platelets from WT (A-B) or Caldaggef1^−/− (C) mice expressing VWF/WT (red bars) was set to 100%. Red bars, platelets expressing VWF/WT only; blue bars, platelets expressing VWF/p.V1316M. Data are shown as mean ± SD; n = 3-13 mice per group. ***P ≤ .001. ns, not significant.