The function of Ensembl gene identifier ENSG00000100985 (MMP9, matrix metallopeptidase 9) is as follows. Matrix metalloproteinase that plays an essential role in local proteolysis of the extracellular matrix and in leukocyte migration (PubMed:12879005, PubMed:1480034, PubMed:2551898). Could play a role in bone osteoclastic resorption (By similarity). Cleaves KiSS1 at a Gly-|-Leu bond (PubMed:12879005). Cleaves NINJ1 to generate the Secreted ninjurin-1 form (PubMed:32883094). Cleaves type IV and type V collagen into large C-terminal three quarter fragments and shorter N- terminal one quarter fragments (PubMed:1480034). Degrades fibronectin but not laminin or Pz-peptide. {ECO:0000250|UniProtKB:P41245, ECO:0000269|PubMed:12879005, ECO:0000269|PubMed:1480034, ECO:0000269|PubMed:2551898, ECO:0000269|PubMed:32883094}.