Neuropilin-1 (NRP1) is a transmembrane glycoprotein expressed by endothelial,dendritic,and regulatory T cells,as well as several other normal cell types and malignant tumor cells. NRP1 was first identified as a semaphorin (SEMA) receptor,involved in axonal guidance in embryonic development. NRP1 was also shown to act as a receptor for vascular endothelial growth factor (VEGF) and a promoter of angiogenesis through its interaction with VEGF-A165 (and other VEGFs) and the receptor tyrosine kinase (RTK) VEGF-R2. NRP1 plays versatile roles in angiogenesis,axon guidance,cell survival,migration,and invasion.