Effects of _IIbβ₃-specific peptidomimetic compounds on (A) AP5 and (B) PMI-1 epitope expression. Washed platelets (1 × 10⁹/mL) were incubated with serial concentrations of synthetic antagonists for 30 minutes at room temperature, and then biotinylated AP5 or PMI-1 was added to the mixtures at a final concentration of 5 μg/mL. After 30 minutes of incubation at room temperature, FITC-conjugated streptavidin was added at a final dilution of 1:320, and bound antibody was analyzed by flow cytometry. Open symbols represent the antagonists that induce AP5 epitope (group I) and solid symbols represent the antagonists that do not induce AP5 epitope (group II). As controls to _IIbβ₃-specific peptidomimetic compounds, RGDW and HHLGGAKQAGDV (H12) were tested. These results are representative of six and three separate experiments, respectively.