NRP1 and neoplasm: αvβ3 integrin is a cell-adhesive receptor that is overexpressed on tumor vessels but not on normal tissue vessels25, 26, 27, whereas Neuropilin-1 (Nrp-1) is a transmembrane receptor that is highly expressed in a variety of human carcinoma cells and is correlated with angiogenesis and vascular permeability28.