Inhibitory effects of H-RN on HUVEC differentiation into capillary structures. HUVECs were starved overnight and pre-incubated with different concentrations of H-RN and scrambled peptide for 30 min. VEGF (100 ng/ml) was added for peptide-treated and VEGF groups, and cells were seeded into Matrigel-coated wells. A, no-VEGF; B, 100 ng/ml VEGF; C, 100 ng/ml VEGF + 1 mM H-RN; D, 100 ng/ml VEGF + 1 mM scrambled peptide. VEGF (100 ng/ml) strongly stimulated HUVEC tube formation. H-RN significantly inhibited VEGF-stimulated HUVEC tube formation, particularly at 1mM. Scrambled peptide did not show inhibitory effects on HUVEC tube formation (magnification ×200). E: Quantitative analysis of tube formation under different experimental conditions using Image Program Plus software. Values represent the mean tube lengths from three independent experiments (*p<0.05, each condition versus VEGF control group).