A protein that is made by the body and that helps dissolve blood clots. It can also be made in the laboratory and is used in the treatment of heart attack and stroke. It is also being studied in the treatment of cancer. r-tPA belongs to the family of drugs called systemic thrombolytic agents. Also called recombinant tissue plasminogen activator, tissue plasminogen activator, tPA, Activase and Alteplase.