The function of TFPI (tissue factor pathway inhibitor, Ensembl gene identifier ENSG00000003436) is as follows. Inhibits factor X (X(a)) directly and, in a Xa-dependent way, inhibits VIIa/tissue factor activity, presumably by forming a quaternary Xa/LACI/VIIa/TF complex. It possesses an antithrombotic action and also the ability to associate with lipoproteins in plasma. .