Angiogenesis, formation of new blood vessels from pre-existing vessels is a hallmark of many eye diseases such as age-related macular degeneration, proliferative diabetic retinopathy, retinopathy of prematurity and vascular glaucoma, which are among leading cause of visual loss in the USA and throughout the world. Vascular endothelial growth factor (VEGF), the major stimulator of angiogenesis, elicits its effect by binding to and activating two endothelial receptors namely VEGFR-1/FLK-1 and VEGFR-2/FLT-1. Although activation of VEGFR-2 has been demonstrated to be an essential requirement for induction of angiogenesis, the role of VEGFR-1 in angiogenesis is largely unknown. We will investigate the molecular mechanisms responsible for action of VEGFR-1, such as activation of signaling molecules or induction of immediate early genes (IEG) that might drive its anti-angiogenesis effects in endothelial cells. The significance of the results obtained from the proposed study lies in their potential to provide fundamental information on how VEGFR-1 communicates to control/restrain angiogenesis in endothelial cells. The importance of angiogenesis in ocular diseases is well recognized. our long-term goal is to begin to apply the information obtained from this project to the design of strategies to regulate angiogenesis in clinical settings.