Fibronectin, a glycoprotein present in a soluble dimeric form in plasma, and in a dimeric or multimeric form at the cell surface and in extracellular matrix. Fibronectin is involved in cell adhesion and migration processes including embryogenesis, wound healing, blood coagulation, host defense, and metastasis. Cellular fibronectin is a 550KDa glycorpotein existing as two heterodimers,different from plasma fibronectin in the presence of additional polypeptide segments and in altering morphology of transformed cells and hemaglutination.