Rapamycin inhibits platelet spreading but has no effect on clot retraction. (A) Spreading of PDK1^f/f and PDK1^−/− platelets on immobilized Fg in the presence of dimethylsulfoxide, 10 μM SB, 1 μM mTORC1 inhibitor rapamycin (Rapa), or 10 μM SB plus 1 μM Rapa. (B) Quantification of area (pixel number) in 4 random fields (mean ± standard error of the mean). Statistical analysis was performed using the Student t test. Rapa partially inhibited the spreading of PDK1^f/f platelets, which was overcome by 10 μM Gsk3β inhibitor SB. Rapa had no further inhibitory effects on spreading of PDK1^−/− platelets. (C) Phosphorylation of Akt T308, Akt S473, and Gsk3β S9 in PDK1^f/f and PDK1^−/− platelets spreading on Fg in the presence of dimethylsulfoxide, 10 μM SB, 1 μM Rapa, or 10 μM SB plus 1 μM Rapa. (D) Clot retraction of PRP containing PDK1^f/f and PDK1^−/− in the presence of dimethylsulfoxide, 1 μM Rapa, or 1 μM Rapa plus 10 μM SB. (E) Two-dimensional clot retraction was measured using National Institutes of Health Image J software, and the data were expressed as retraction ratios (mean ± standard error of the mean from 3 separate experiments). Statistical significance was calculated using a Student t test. Rapa did not inhibit clot retraction of PRP-containing PDK1^f/f platelets and did not further inhibit clot retraction of PRP-containing PDK1^−/− platelets.