Endothelial protein C receptor (EPCR), also known as CD201, is a 46 kD N-glycosylated type I transmembrane protein primarily expressed on the endothelial cells of arteries and veins in heart and lung. It is also expressed at high levels on a subset of hematopoietic stem cells and a subset of dendritic cells. CD201 functions as a primary receptor for protein C activation, which results in inhibition of both intrinsic and extrinsic coagulation pathways. It also plays an important role in many pathophysiologic processes, such as inflammation responses to infection, trauma, hematopoiesis, and autoimmune response. Deletion of the CD201 gene in knock-out mice leads to embryonic lethality before embryonic day 10, indicating that CD201 expression is critical for embryo development. In humans, mutations of CD201 have been associated with venous thromboembolism and myocardial infarction as well as with late fetal loss during pregnancy.