KDR, alternative name Flk-1 (type 2 receptor), is one of the receptors for VEGFs, important growth factors for vasculogenesis, angiogenesis and lymphangiogenesis. Flt-1 (type 1 receptor) is also known as a VEGF receptor. In particular, it is believed that they play important roles in the signal transduction of endothelial and lymphatic endothelial cells. It is understood that after binding with VEGF, Flt-1 and KDR/Flk-1 stimulate the vascular endothelial cells in a coordinated action. This monoclonal antibody recognizes KDR by W.B. and I.P. applications and it enables FACS analysis of KDR-expressing cells. It has been confirmed that the addition of this antibody does not induce ligand-binding-dependent phosphorylation of KDR and it may be used as a neutralizing antibody.