Description: The FN-3 monoclonal antibody recognizes human fibronectin, a component of the extracellular matrix. This high molecular weight protein (almost 400 kDa) exists as an extracellular and a soluble plasma form. Fibronectin functions in cell adhesion and migration via integrins present on the interacting cell. Fibronectin also associates with collagen, actin and fibrins. In malignancies, fibronectin protein levels can be altered. In lung carninomas, expression is decreased. The FN-3 antibody recognizes a determinant on human cellular but not plasma fibronectin; this recognition is not lost upon trypsin treatment. Furthermore, FN-3 antibody has been shown to crossreact to bovine fibronectin.