Alanine substitution in peptide 12. (A) Peptides whose sequence differs from that of peptide 12 for the substitution of one residue with Ala were covalently linked to microtiter plates. A “scrambled” version of peptide 12 (sP12) and BSA, as a negative control, were also tested. HUVECs were added to the plates and allowed to adhere. Results are expressed as percentage of cell adhesion observed on peptide 12-coated plates. (B) Purified α5β1 integrin was added to wells coated with the same peptides as in panel A, and bound integrin was detected by using an anti-α5β1 antibody and a colorimetric assay. Data are expressed as percentage of protein binding on peptide 12-coated plates. (C) Biotinylated VEGF-A was added to wells coated with peptide 12, 1, 7, VEGFR-1/Fc, as a positive control, or BSA, as a negative control. The amount of attached VEGF-A was quantified by incubation with streptavidin alkaline phosphatase-conjugated and a colorimetric assay. Representative experiments performed in triplicate are shown; data are mean plus or minus SEM.