Edg receptors constitute of family of 8 GPCRs (designated as Edg-1 through Edg-8) that can be further sub-classified as sphingosine 1-phosphate receptors (S-1-P) and lysophosphatidic acid (LPA) receptors. The Edg-1 receptor is an S-1-P receptor that is coupled to a variety of intracellular responses via Gi and Go. The Edg-1 receptor was initially cloned as an immediate-early gene induced during differentiation of human endothelial cells, an in vitro model of angiogenesis. It has been shown to play a critical role in regulating cellular proliferation and survival.