VIIa and TF mAB binding to cholesterol-depleted cells. Control and cholesterol-depleted cells were incubated with varying concentration of ¹²⁵I-VIIa in the presence and absence of anti-TF IgG (A) or ¹²⁵I-TF mAB (B) for 2 hours at 4°C. At the end of the 2-h incubation, the unbound ligands were removed, cells were washed, and the cell-associated radioactivity was counted. Specific VIIa binding, shown in panel A, was determined by subtracting the nonspecific binding (VIIa binding to cells in the presence of anti-TF IgG) from the total binding (VIIa binding in the absence of anti-TF IgG) (n = 4 to 6, mean ± SE).