Mouse platelet aggregation test with washed platelets. Platelets were labeled with CD9-PE or CD9-APC and mixed in 1:1 ratio before stimulation. Aggregation was measured by flow cytometry in time after stimulation with PMA (A), collagen (B), Aggretin A (C), and botrocetin (D). Average and standard error of the mean are depicted when indicated, n > 3. Colored asterisks at each data point indicate statistical significance with the unstimulated control (P < .05). Representative data out of at least 5 independent experiments are depicted. We combined the agonists with the following antagonists: tirofiban (integrin β3 inhibitor), blocking anti-CD29 antibody (integrin β1), Bay (Syk inhibitor), and JAQ1 (GPVI blocking antibody). (E) An example of the gating used after flow cytometry analysis is depicted. Note the increase in events in Q2 after stimulation with Aggretin A. All populations are plotted against the forward and side scatter and indicated by colored arrowheads. PLT, platelets.