2.6. Platelet aggregation assay

Platelet aggregation was assessed by light transmission aggregometry in a PAP‐8E (Bio/Data Corporation) aggregometer for up to 30 min. Washed platelets were incubated with aPT antibodies for 5 min with an antiprothrombin antibody (50 μg/ml) followed by CaCl₂ (1 mM, 3 mM, or 10 mM) and purified human prothrombin (1 µM). In some studies, platelets were preincubated with eptifibatide (9 µM), vorapaxar (1 µM) + BMS‐986120 (1 µM), indomethacin (10 µM), ticagrelor (10 µM), PRT‐060318 (5 µM), dasatinib (10 µM), mAb IV.3 (10 µg/ml), or rivaroxaban (200, 400, 800, or 1000 nM) for 10 min.