Compound 1 inhibits binding of a fluorescent cyclic RGD peptide to αIIbβ3. Purified αIIbβ3 (300 nM) was incubated with buffer alone, DMSO, tirofiban (1 μM), compound 1, or a functionally inactive derivative of compound 1. FITC-labeled c(KRGDf) was added at 10 nM and after 10 minutes at 22°C fluorescence polarization was assessed. Binding is presented as mean plus or minus SD for 3 separate experiments, calculated as the percentage of the maximum mP value observed in the presence of buffer alone. The mP observed with tirofiban treatment was taken as background.