Quantitative analysis of VAMP isoforms and cargo in spread platelets. Double immunofluorescence microscopy of actin and (A) VAMP-8, (B) serotonin, (C) VWF, (D) VAMP-7, (E) TIMP2, or (F) VEGF. Scale bars, 5 μm. (G) Images were evaluated as described in supplemental Figure 3 to demarcate the granulomere of the spread platelets and subsequently analyzed to quantify the amount of VAMP-8, serotonin, VWF, VAMP-7, TIMP2, and VEGF associated with the granulomere (black) versus the periphery (red). Error bars represent the standard deviation (SD) of measurements from 250 to 350 platelets per condition.