Thrombospondin-1 (TSP-1) is a 150-180kDa calcium-sensitive protein that is secreted as a disulfide-linked homotrimer. TSP-1 regulates a wide range of cellular functions including their interactions with other cells and with the extracellular matrix (ECM). TSP-1 contains an N-terminal Laminin G-like globular domain, an extended central region with one vWFC domain, 3 TSP type 1domains, 2 EGF-like domains, and 8 TSP type3 domains, and a globular TSP C-terminal domain. Distinct regions of TSP-1 have been associated with binding to particular ECM or cellular molecules. TSP-1 counteracts the angiogenic, hypotensive, and antithrombotic effects of nitric oxide (NO). It binds and neutralizes VEGF, blocks VEGF R2 signaling on vascular endothelial cells(EC), and destabilizes adhesive contacts between EC. TSP-1 also plays an important role in wound repair and tissue fibrosis by binding latent TGF-beta and inducing release of the active cytokine from the latency associated peptide (LAP).