Fig. 2.

Overview of fibrinolysis. Single-chain (sc) tPA and uPA are secreted from endothelial cells and from renal epithelium, monocytes/macrophages, or endothelial cells, respectively. Both tPA and uPA can be inhibited by plasminogen activator inhibitors (PAI-1 and PAI-2). Once plasmin is generated, it converts single-chain tPA and uPA to two-chain (tc) forms. Plasminogen is converted into the active protease plasmin primarily by tc-tPA (with fibrin as a cofactor) or tc-uPA. Plasmin cleaves fibrin to fibrin degradation products (FDPs), which can be inhibited by TAFI. Plasmin itself is inhibited by α2-antiplasmin (α2-AP) and α2-macroglobulin (α2-M).