Fibronectin is an ubiquitous extracellular glycoprotein that exists in a soluble form in body fluids and in an insoluble form in the extracellular matrix. It plays a major role in many important physiological processes, such as embryogenesis, wound healing, hemostasis and thrombosis. Fibronectin is secreted as a dimer with a monomer molecular weight of 220–250 kDa. It is synthesized by, and present around, fibroblasts, endothelial cells, chondrocytes, glial cells, and myocytes. Fibronectin´s importance during cancer progression has further been shown. It represents an active element in the process of T cell activation in the immune cascade triggered by organ transplantation.