Effect of P2Y12 knockout and ADP receptor antagonists on platelet spreading. (A) WT or P2Y12-/- mouse platelets were treated with A3P5P (0.5 mM) or control and spread on fibrinogen for 2 hours, fixed, permeabilized, stained, and observed as previously described. Representative pictures. (B) The surface areas of individual platelets were measured (mean±SE). Difference between groups was analyzed using Student’s t test. Numbers of platelets analyzed are indicated above the bars. Data are from 3 experiments. (C) Human platelets were treated with 2-MeSAMP (50 μM), A3P5P (0.5 mM), both, or control, and spread on fibrinogen for 1 hour as described in (A). (D) Quantitation of (C) performed as in (B). (E) A schematic depicting the regulatory mechanisms and roles of the PI3K/Akt pathway in integrin-mediated platelet spreading.