It does three important things. It basically calls upon platelets. Now, platelets are these pieces of megacaryocytes that are also used to form that meshlike network of blood clots that creates that seal and prevents that movement of liquid of blood out of that blood vessel. So Thrombin calls upon our platelets. And by the way, prothrombin is formed in the liver, it's released by the liver cells into our blood. So it circulates within our blood and it's activated by this complex prothrombinase.