tissue plasminogen activator

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A clot-dissolving enzyme that is produced naturally by cells in the walls of blood vessels and catalyzes the conversion of plasminogen to plasmin.
• noun A preparation of this enzyme that is produced by genetic engineering and used to dissolve clots blocking coronary arteries in heart attack and cranial arteries in certain cases of stroke.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun a thrombolytic agent (trade name Activase) that causes fibrinolysis at the site of a blood clot; used in treating acute myocardial infarction