Peptide 12 sustains vessel formation in vitro. HUVECs were incubated on 24-well plates precoated with a type I collagen gel mixture, in the absence (A) or presence of peptide 12 (B), peptide Q225A (D), or peptide Y220A (E). VEGF-A was used as a reference control (C). To assess the specificity of peptide 12 activity, an antibody against peptide 12 was also tested in combination with peptide 12 (F). Results are representative of 3 independent experiments. Bars represent 25 μm in C, 50 μm in the others.