Direct interaction of angiostatin with Mac-1. The binding of fibrinogen (A) or ICAM-1 (B) to immobilized Mac-1 is shown in the absence or presence of increasing concentrations of K1-4 (▴), K1-3 (▪), or K4 (○). (C) Dose-dependent specific binding of the isolated I-domain of Mac-1 to immobilized K1-4 (▴), K1-3 (▪), or K4 (○). Specific binding is expressed as absorbance at 405 nm. Data are mean ± SD (n = 3) of a typical experiment; similar results were observed in 3 separate experiments.