Role of MRP4 in bleeding and thrombosis. (A) Carotid artery thrombosis was induced by placing a 15% ferric chloride patch on the artery for 4 minutes, and the time to occlusion was recorded (n ≥ 8 animals in each group) (***P < .0001). (B) Tail bleeding time in WT and MRP4^−/− mice (n = 9) (**P < .001). (C) Hemoglobin concentration in the chamber effluent (containing 10 ml NaCl) was measured by the Drabkin method (n ≥ 5 animals in each group) (***P < .001). (D) Platelet-depleted WT mice were injected with WT or MRP4^−/− washed platelets (plts). Platelet count was checked to be higher than 3 × 108 platelets per milliliter in each animal, and the lateral tail vein was cut as described in supplemental Methods. Blood loss was measured and normalized to WT (n ≥ 5 animals in each group) (*P < .05).