Platelet-specific PDK1 deficiency causes thrombocytopenia, inhibits platelet aggregation in response to low doses of agonists, and delays FeCl₃-induced occlusion of the carotid artery. (A) Genotyping results of PDK1^f/wt, PDK1^f/f, and PDK1^−/− using polymerase chain reaction. (B) PDK1 deficiency causes a 25% decrease of peripheral blood platelet counts (P < .05. n = 20). (C) PDK1 deficiency did not enhance Annexin V binding to platelets. (D) Washed platelets were prepared from PDK1^f/f and PDK1^−/− mice; western blot results showed that PDK1 was depleted in PDK1^−/− platelets. (E) The aggregation of PDK1-deficient platelets was diminished in response to low doses of thrombin. (F) The aggregation of PDK1-deficient platelets was diminished in response to low doses of U46619. (G) The aggregation of PDK1-deficient platelets was diminished in response to low doses of ADP. (H) The mouse carotid artery was treated with 10% FeCl₃, as described. Traces of blood flow in the carotid arteries of PDK1^−/− and PDK1^f/f mice were presented, respectively. The times to occlusion were measured (n = 5).