Effect of dominant-negative ELF-1 peptide on endothelial migration, tube formation, and in vivo angiogenesis. (A) Effect of peptide A1 on Ang-1–dependent endothelial migration compared with the mutant peptide (Mutant A1). The concentration of Ang-1 was 100 ng/mL (*P < .05 compared with control). (B) Effect of peptide A1 (10 μM) or mutant A1 (10 μM) on cell growth. (C) Endothelial tube formation on Matrigel supplemented with bFGF (20 ng/mL) at 8 hours and 24 hours in the presence of the mutant peptide A1 (10 μm) or peptide A1 (5, 10 μm) compared with no peptide (control). Quantitation of endothelial tube formation at 24 hours (*P < .05 compared with control). (D) Effect of peptide A1 and mutant peptide A1 on angiogenesis in vivo using the Matrigel plug assay (supplemented with bFGF; 80 ng/mL). The dissected Matrigel plug and accompanying immunostaining for CD31 (PECAM-1) are shown. Determination of vessel density within the Matrigel plug per high-power field (hpf) (*P < .05 compared with peptide A1). Data are presented as means ± SE.