Physiology of thrombospondin.

Thrombospondin is a large, multifunctional glycoprotein released from activated platelets and secreted by growing cells. It binds to components of the cell surface and extracellular milieu. Thrombospondin probably modulates a number of processes, including aggregation of platelets, formation and lysis of fibrin, adhesion and migration of cells, and progression of cells through the growth cycle. Studies relating thrombospondin to disease processes are just beginning.