The binding of ¹²⁵I-VN to immobilized αvβ₃ integrin was carried out in the absence (no additives) or presence of cRGDfV (10 μg/mL), PAI-1 (200 nmol/L), and HK or HKa (170 nmol/L each) in a TBS buffer containing 50 μmol/L ZnCl₂. Nonspecific binding was counted in the presence of 100-fold excess “cold” VN. Data are expressed as counts per minute (cpm)/well. Moreover, specific binding was estimated (by subtracting the nonspecific binding from the total), and data are also expressed as percentage of control, which is represented by the specific binding in the absence of additives. Data are mean ± SEM (n = 3) of a typical experiment; similar results were obtained in 3 separate experiments.