Fig. 3. Inhibition of the interaction between vβ5-integrin and vitronectin increases fibronectin-matrix assembly. (A) MG-63 cells were pre-incubated for 45 minutes with the cyclic peptide RGDfV (20 µM) or its inactive analog RADfV (20 µM) or for 2 hours with 20 µg/ml of normal mouse IgG, β3-integrin-blocking antibody LM609 or β5-integrin-blocking antibody P1F6; cells were then incubated with [¹²⁵I]fibronectin (Fn) for 6 hours. The data shown here are representative of three separate experiments. Data are the mean ± s.e. of two different experiments performed in duplicate. ^*Significantly different than control cells, t-test, P<0.05 (n=4), significantly different than control cells (t-test). (B) Same as A only under conditions of uPAR stimulation with P25. Cell layers were extracted in 1% DOC, and [¹²⁵I]fibronectin that was incorporated into the detergent-insoluble matrix was recovered by centrifugation and measured by -scintillation. This experiment is representative of three separate experiments. Data are the mean ± s.e. of two experiments performed in duplicate. ^*P<0.05 (n=4), significantly different than P25-treated cells (t-test).