Inhibition of LRP/CD91-mediated endocytosis of ¹²⁵I-Hx-heme and ¹²⁵I-Hx. (A) The effect on endocytosis ¹²⁵I-Hx-heme and ¹²⁵I-Hx by RAP (100 μg/mL), rabbit anti-LRP/CD91 IgG (300 μg/mL), nonimmune rabbit IgG (300 μg/mL), Hx-heme (100 μg/mL), Hx (100 μg/mL), and heme (50 μg/mL). The experimental conditions were otherwise as described in the legend for Figure 4. (B) The effect of various Hx-heme concentrations on ¹²⁵I-Hx-heme endocytosis. Values shown in panels A and B represent the mean ± SD of triplicate determinations.