the facts that epithelium releases plasminogen activator and that plasmin , generated from plasminogen by an activator , can degrade both fibrin and fibronectin , as well as the laminin component of the subepithelial basement membrane , would suggest that the plasminogen activator-plasmin system effect degradation of those macromolecules , thus initiating the events that lead to eventual , frank stromal ulceration .
C0022984
laminin
C0004799
basement membrane