The endothelial cell as the maestro of thromboregulation. Non-thrombogenic functions shown in green include the thrombomodulin–thrombin protein C system, tissue factor pathway inhibitor, plasmin generating system, and the heparin antithrombin system. Additionally, there are non-thrombogenic interactions with platelets through CD39, nitric oxide, and the eicosanoid pathway. Non-constitutive “activated” functions (red) on the luminal side of the cell include upregulation of cell adhesion molecules and tissue factor, factor IX_a binding, platelet activating factor release (PAF), factor V synthesis, and basally: PDGF release and plasminogen-activated inhibitor–1 release. Abluminal matrix deposition of collagen, vWF, fibronectin and thrombospondin are also shown.