Tissue plasminogen activator (t-PA) is a protein involved in breaking down the blood clot.
It is a serine protease found in the endothelial cells that line the blood vessels.

Like any enzyme, it converts plasminogen into plasmin, the main blood clot lysis enzyme. Due to its lysis activity, t-PA is used in clinical medicine to treat cerebral embolism and thrombosis.
Its use is contraindicated in cases of cerebral hemorrhage or head trauma.