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. So once we form Thrombone, it calls upon platelets, it also activates another fiber protein known as Fibrinogen. And fibrinogen basically is activated into fibrin. So Fibrin is the active form of Fibrinogen, which is activated by Thrombin.