PI3K-C2α controls membrane dynamics and mechanical forces. (A) Washed platelets stimulated in suspension with CRP (10 µg/mL) and thrombin (0.5 IU/mL) were visualized by scanning electron microscopy. Images of 2 WT and PI3K-C2α^WT/D1268A platelets are representative of 5 mice. Scale bar: 1 µm. Arrows show filopodia. Filopodia mean number was quantified per platelet (mean ± SEM; n = 3; *P < .05 and **P < .01 vs WT according to 2-tailed Student t test). (B) Schematic representation of AFM technique “force mapping mode,” using a cantilever with tip to record platelet topography and measure the Young’s modulus, inverse reflection of platelet elasticity. Washed platelets were placed on a fibrinogen-coated surface for 45 minutes in the presence of thrombin (0.5 IU/mL). Representative AFM images are shown and arrows indicate membrane invaginations. Scale bar: 1 µm. Quantitative determination of the local mechanical properties of live platelets was carried out by atomic force microscopy (JPK NWII), operating in force distance mode in liquid buffer solution at 37°C. The bar graph represents the platelet mean Young’s modulus (mean ± SEM; n = 3; **P < .01, according to 2-tailed Student t test).