Inhibits trypsin and plasmin, but not thrombin, coagulation factor Xa, or urokinase-type plasminogen activator (PubMed:11604408). May play a role in cell differentiation (PubMed:30045019). Interacts with SLFN12; as part of a pathway regulating cell differentiation (PubMed:30045019). May interact with USP14 (PubMed:30045019). Expressed in many tissues, including brain, bone marrow, lymph node, heart, lung, liver, pancreas, testis, ovary, and intestine. Belongs to the serpin family. Ov-serpin subfamily.