Serine protease that cleaves extracellular substrates, and contributes to the proteolytic processing of growth factors, such as HGF and MST1/HGFL. Plays a role in cell growth and maintenance of cell morphology. Plays a role in the proteolytic processing of ACE2 (By similarity). Mediates the proteolytic cleavage of urinary UMOD that is required for UMOD polymerization (PubMed:26673890). Cleavage after basic amino-acid residues, with Arg strongly preferred to Lys. Detected in kidney, in thick ascending tubule epithelial cells (at protein level) (PubMed:26673890). Detected in kidney and liver (PubMed:9395459, PubMed:9435303). No visible phenotype. Mice are viable and fertile (PubMed:9435303, PubMed:11127869). They present no defect in blood coagulation (PubMed:9435303). Likewise, they present no defect in liver regeneration after liver resection (PubMed:11127869). Mice have severely impaired hearing, with abnormal morphology of the tectorial membrane in the cochlea, but no visible defects of the organ of Corti and no loss of inner or outer hair cells. Mutant mice have reduced levels of thyroid hormone. This may play a role in their hearing deficit, since adequate levels of thyroid hormone are required for normal development of the auditory system (PubMed:17620368). Urine from mutant mice lacks normally processed Umod; contrary to wild-type, urinary Umod from mutant mice does not polymerize into long fibers (PubMed:26673890). Minor isoform. Major isoform. Belongs to the peptidase S1 family.