Fibronectin is an extracellular matrix glycoprotein present on most cell surfaces, in extracellular fluids and in plasma. Fibronectin has been shown to also play a role in cellular morphology, cytoskeletal organization, phagocytosis, hemostasis, embryonic differentiation and wound repair. Fibronectin is produced by a wide variety of epithelial and mesenchymal cells in vitro including: fibroblasts, chondrocytes, myoblasts, Schwann cells, macrophages, hepatocytes and intestinal epithelial cells. Cellular fibronectin is present in many tissues including spleen, lymph node, tonsil, blood vessel walls, liver, kidney, muscle, skin, brain and peripheral nerves. It is found in basement membranes and in loose connective tissue stroma. It is also present in platelet α-granules and is expressed on the platelet surface after activation.