Schematic representation of likely “footprints” for patient Abs E1, E2, and E3 and T1, T2, and T3 based on inhibition of Ab binding by mAbs specific for subdomains of the α_IIb and β₃ head regions. The footprint for mAb 7E3 (and abciximab) is shown by the dashed oval. “RGD” indicates approximate location of the binding site for RGD peptide, eptifibatide, and tirofiban.