A 52-year-old man is brought to the emergency department with severe chest pain. Angiography demonstrates a severe coronary occlusion. A thrombolytic agent is administered to reestablish perfusion. Which of the following does the thrombolytic agent activate?

j) Bleeding may also occur spontaneously in patients who have received ______ or thrombolytic drugs, or who have coagulation disorders such as hemophilia.