CD97 is a chemoattractant for HUVECs. (A) CD97-stimulated HUVEC chemotaxis is RGD-dependent and requires at least 3 EGF repeats. Wild-type, RGE mutants, and EGF-like domain deletion fragments were used as chemoattractants in a HUVEC migration assay. Basic fibroblast growth factor (bFGF) was used as a positive control. (B) HUVEC migration to CD97 involves α5β1, αvβ3, and αvβ5 integrins. HUVECs were treated with 20 μg/mL of various function-blocking anti-integrin monoclonal antibodies before being placed into the migration chamber. Results shown are representative of at least 10 replicates. Data show mean number of cells per ×200 microscopic field plus or minus SEM.