SPARC peptides FSEN and FSEC inhibit endothelial cell migration. HUVEC cells were treated with serial dilutions of SPARC peptides with or without 10 ng/ml bFGF in a modified Boyden chamber. Relative stimulation was calculated as percentage of bFGF-induced migration. (A) Peptide FSEN inhibited bFGF-stimulated endothelial migration with an EC50 of ~2 nM. (B) Peptide FSEC displayed a strong dose-dependent inhibition of bFGF-stimulated endothelial migration with an EC50 ~1 pM. Dark circles represent bFGF-stimulated migration; light circles represent basal migration in the absence of an activator.