D-dimer–induced spreading is dependent on GPVI signaling. (A) Glass coverslips were coated overnight with D-dimer as described in "Materials and methods." Human platelets (ptl; 20 × 10⁹/L) were preincubated with dasatinib (3 μM), PRT-060318 (10 μM), or vehicle before being allowed to spread on coated coverslips. Actin staining was performed on fixed platelets with Alexa-488 phalloidin. Scale bar, 5 μm. The figure is representative of 3 similar experiments. (B) Quantification of platelet surface area and platelet count per millimeter squared (n = 3). In each independent experiment, 5 random pictures were analyzed (100 platelets in total). The results are shown as mean ± standard deviation. *P < .05, ***P < .001 compared with control.