My laboratory's research is focused primarily on vascular growth factors and their receptors. In particular, we study growth factor/receptor-mediated mechanisms associated with angiogenesis. Knowledge of these mechanisms is used to develop angiogenesis inhibitors. VEGF is a major regulator of angiogenesis. We recently identified neuropilin-1 (NRP1) as a VEGF receptor that is expressed by endothelial cells (EC) and tumor cells. NRP is also a receptor for semaphorins, chemorepulsants that repel axons and collapse growth cones. We have found that semaphorins are inhibitors of EC motility, suggesting a possible molecular connection in the mechanisms that regulate neuronal and capillary migration. Recently, we cloned a soluble form of NRP1 (sNRP1). sNRP1 is a VEGF antagonist, and its expression in tumor cells results in decreased vascularity and increased tumor necrosis. Together, these results suggest that antagonists of NRP1 are potential antagonists of angiogenesis and tumor progression.