Fibrin strands woven into the clot structure are cleaved into soluble fibrin fragments and then removed by macrophages. The action of fibrinolysis also serves to restore blood flow into the area that had been sealed off, helping to promote further healing. Fibrinolysis is mediated by a proteolytic enzyme called plasmin (plasminogen is the inactive precursor form of plasmin that is found in plasma). Plasmin takes on fibrinolytic properties after activation, digesting both fibrin and fibrinogen. Inhibitors act to control the process, serving as a check and balance system for fibrinolytic activities.