Coagulation factor (F)XI has been described as a component of the early phase of the contact pathway of blood coagulation, acting downstream of factor XII.In contrast to its mild hemostatic activities, FXI is known to play a significant role in thrombosis, as it is a demonstrated independent risk factor for deep vein thrombosis, ischemic stroke, and myocardial infarction. A better understanding of the varied and complex role of FXI in both thrombosis and hemostasis will help to allow better prediction of bleeding risk in FXI-deficient patients and also informing the development of targeted agents to inhibit the thrombotic activities of FXI while preserving hemostasis.

> 95% as determined by Bis-Tris PAGE; > 95% as determined by HPLC