GPIbα is required for thrombin-induced ROS generation. Human platelets +/− Nk protease treatment, and labelled with 10 µM H2DCFDA,were stimulated with (A) 2 U/mL thrombin (B) 10 µg/mL CRP, (C) 250 µM PAR4-AP or (D) 50 µM PAR1-AP, and ROS production was measured by flow cytometry. Data are mean±SEM (n=4). (E) Washed human platelets +/− Nk protease treatment were stimulated with 250 µM PAR4-AP for 3 min and monitored for platelet aggregation by light transmission aggregometry using a PAP4 platelet aggregometer. Data are mean±SEM (n=4). (F) H2DCFDA labelled mouse platelets +/− Nk protease treatment were stimulated with thrombin (2 U/mL) and monitored for ROS production by flow cytometry. Data are mean±SEM (n=3). *P≤0.05, **P≤0.01, ***P≤0.001. ns=statistical nonsignificance.