Simplified representation of blood coagulation, indicating the 3 anticoagulant pathways (in orange/red). Agents that have recently been shown to target the anticoagulant pathways and that are proposed as potential therapies for hemophilia are indicated in dark blue text, and their actions are shown by a dark blue “×.” For simplicity, only thrombin is shown to be inhibited by antithrombin. APC, activated protein C; AT, antithrombin; PS, protein S; TFPI, tissue pathway inhibitor. Professional illustration by Somersault18:24.