ERp5 is expressed in vivo in the developing thrombus. Anti-ERp5 antibody labeled with Alexa Fluor 488 (0.05 µg/g body weight) or preimmune IgG labeled with Alexa Fluor 488 (0.05 µg/g body weight) and anti CD-42b antibody labeled with DyLight 649 (0.1 µg/g body weight) were infused into a mouse 5 to 10 minutes prior to arteriolar injury. (A) Median total integrated fluorescence for anti-ERp5 (black; 24 thrombi from 3 mice) compared to median of the total integrated fluorescence for control IgG (gray; 27 thrombi from 3 mice); **P < .005. (B) Mice were injected intravenously with eptifibatide (10 µg/g body weight) 10 minutes prior to vessel injury and every 20 minutes after initial injection, and the experiment in panel A was repeated. Median total integrated fluorescence vs time after vessel injury for anti-ERp5 antibody (black) and IgG control (gray) is shown. Platelet accumulation (C) and fibrin generation (D) were measured before (1) and after the injection of eptifibatide alone (2) or eptifibatide followed by anti-ERp5 antibody (3 µg/g body weight) (3). *P < .05;***P < .001. F, median fluorescence intensity.