The function of SERPINI1 (serpin family I member 1, ENSG00000163536) is as follows. Serine protease inhibitor that inhibits plasminogen activators and plasmin but not thrombin (PubMed:11880376, PubMed:19265707, PubMed:19285087, PubMed:26329378, PubMed:9442076). May be involved in the formation or reorganization of synaptic connections as well as for synaptic plasticity in the adult nervous system. May protect neurons from cell damage by tissue-type plasminogen activator (Probable). {ECO:0000269|PubMed:11880376, ECO:0000269|PubMed:19265707, ECO:0000269|PubMed:19285087, ECO:0000269|PubMed:26329378, ECO:0000269|PubMed:9442076, ECO:0000305}.