By degradation of cell adhesion molecules, metalloproteases increase the motility of epithelial cells. Growth factors, which are bound to the plasma membrane, are released. In this way, the growth factors can reach their receptors on target cells. Growth factors, for example TGF-b, may bind to components of the extracellular matrix. By degradation of such components, growth factors are released. Growth factor receptors, which are released from the cell membrane, can no longer signal. They may act as traps for growth factors. Binding proteins, which inhibit the action of growth factors, are degraded. In this way, growth factors become active. Proteases assist tumor invasion by degrading the basement membrane. Cleavage products from the extracellular matrix may exert biological activity such as the stimulation of angiogenesis.