The 5 EGF-like isoform of CD97 stimulates invasion. (A) E/1-5-RGD-FL is a potent chemoattractant for HUVEC invasion through Matrigel. The use of RGD to RGE mutants demonstrates that an intact RGD sequence in CD97 contributes to maximal stimulation of HUVEC migration through Matrigel. All 5 EGF repeats are also necessary. Basic FGF was used as a positive control. (B) α5β1, αvβ3, and αvβ5 integrins play a role in HUVEC invasion to E/1-5-RGD-FL. Cells were treated with integrin function-blocking antibodies for 30 minutes before being added to the invasion chamber. Alternatively, cells were treated with 300 μM RGD peptide inhibitor for 30 minutes before initiation of the invasion assay. Results shown are representative of at least 10 replicates. Data show mean number of cells per ×200 microscopic field plus or minus SEM.