May play a role in the regulation of plasmin-mediated matrix remodeling. Inhibits trypsin, plasmin, factor VIIa/tissue factor and weakly factor Xa. Has no effect on thrombin (By similarity). Finds in a complex with ABCB1, TFPI2 and PPP2R3C; leading to the dephosphorylation of ABCB1. Highly expressed in placenta. Also expressed in liver and kidney. This inhibitor contains three inhibitory domains.