Fig. 4. VEGFR-1 is involved in EC migration. (A) VEGFR-1/Fc was included in the lower chamber (chemotaxis), in the upper chamber (chemokinesis) or in both, at the indicated concentrations (µg/ml). EGF (100 ng/ml) was used as a positive control, and 0 indicates the presence of only the basal migration medium in the chamber. (B) Specific inhibition of VEGFR-1-induced migration by anti-5ß1 antibodies. Cells were preincubated for 45 minutes at room temperature with the anti-5ß1 mAb, or with an unrelated anti-6 integrin mAb (unrelated Ab), before seeding. Histograms represent the percentage of inhibition of the chemotactic response induced by either VEGFR-1/Fc (5 µg/ml) or EGF (100 ng/ml). (C) Haptotaxis assay was performed on filters in which the underside was coated with 10 µg/ml BSA, VEGFR-1/Fc (VEGFR-1) or vitronectin (VN). (D) Specific inhibition of VEGFR-1 induced haptotaxis by anti-5ß1 antibodies. Cells were preincubated for 45 minutes at room temperature with the anti-5ß1 mAb, or with an unrelated anti-6 integrin mAb (unrelated Ab), before seeding. Histograms represent the percentage of inhibition of the haptotactic response induced by either VEGFR-1/Fc or vitronectin (VN). In every experiments, migration was monitored in a Boyden chamber assay by counting 12 high-power fields for each condition. Histograms represent the mean value ± s.d.