Inhibition of the binding of ¹²⁵I-labeled anti-RGD antibody-enriched F(ab′)₂ fragments of IVIg to Fn by soluble RGD-containing peptide AVTGRGDSPA (□) and the control ARTGVGSPDA peptide (◊). The amount of anti-RGD F(ab′)₂fragments (0.084 μmol per well) was chosen to obtain the binding of 1,000 cpm per well in the absence of competitor peptide. The mean values ± SEM obtained in two independent experiments conducted in duplicates are depicted. The difference between the levels of inhibition obtained was significant and calculated by using the Mann-Whitney test.