Combined inhibition of GPVI with GPIb or α₂β₁ abolishes collagen-induced thrombus formation. Blood was treated with the indicated combination of antagonists before perfusion over collagen: 10B12 at 100 μg/mL and 6F1 at 10 to 20 μg/mL, GFOGER-GPP at 500 μg/mL or 12G1 Fab₂ at 40 μg/mL perfused over collagen as in Figure 1. (A) Surface coverage of platelet deposition or OG488-labeled annexin V binding (mean ± SE, from 4-6 donors). **P < .001, and *P < .05 compared with single antibody controls. (B) Representative phase-contrast images after perfusion, also showing visible collagen fibers. Original magnification, × 60.