Endothelial Protein C Receptor (EPCR) is a Vitamin K-dependent Serine Protease that plays a major role in blood coagulation. Binding of Protein C to EPCR leads to the proteolytic activation of PAR1 (Protease-Activated Receptor 1) on endothelial cells and subsequent up-regulation of Protein C-induced genes. EPCR is a type I transmembrane glycoprotein in the CD1/MHC family. It is expressed most strongly in the endothelial cells of arteries and veins in heart and lung. Membrane bound EPCR is released by metalloproteolytic cleavage to generate the soluble receptor. The extracellular domain of human and mouse EPCR shares approximately 61% amino acid sequence homology. EPCR plays an important role in augmenting Protein C activation by the Thrombin-Thrombomodulin complex and in regulating blood coagulation and inflammation. EPCR is found primarily on endothelial cells. Deletion of EPCR function results in embryonic death, at least in part due to placental thrombosis.