Application of LCKLSL in two in vivo models (in chicken chorioallantoic membrane and murine Matrigel plug assays) of angiogenesis demonstrates suppression of the angiogenic responses. Treatment with the LCKLSL peptide significantly decreases the vascular length. At a dose of 5 μg/mL, the LCKLSL peptide significantly decreases the number of vascular branches, junctions and end-points.