Correspondence Address: Bos, R.; Gaubius Laboratory, IVVO-TNO, PO Box 430, 2300 AK Leiden, Netherlands Chemicals/CAS: fibrin, 9001-31-4; plasminogen activator inhibitor 1, 140208-23-7; tissue plasminogen activator, 105913-11-9; urokinase, 139639-24-0; Antibodies, Monoclonal; Drug Carriers; Fibrin, 9001-31-4; Plasminogen Activator Inhibitor 1; Tissue Plasminogen Activator, EC 3.4.21.68; Urinary Plasminogen Activator, EC 3.4.21.73