Protease-activated receptors in vascular biology

G protein-coupled protease-activated receptors (PARs) provide one answer to the question of how coagulation factors and other proteases regulate cellu lar behaviors. In concert with the coagulation cascade, these receptors pro vide an elegant mechanism that links mechanical information in the form of tissue injury or vascular leak to cellular responses. Roles for PARs in hem ostasis and thrombosis, inflammation, and perhaps even blood vessel develop ment are beginning to emerge. Our current understanding of the role of PARs in platelet and endothelial cell activation and their potential importance in normal and disease states is discussed.