Mucin 20, cell surface associated is a member of the mucin protein family. Mucins are high molecular weight glycoproteins secreted by many epithelial tissues to form an insoluble mucous barrier. The shorter isoform expressed by this gene is localized to the plasma membrane, whereas the longer isoform might be secreted. The C terminus of this protein associates with the multifunctional docking site of the met proto-oncogene and suppresses activation of some downstream met signaling cascades. The protein features a tandem repeat domain that varies between 2 and 6 copies in most individuals. The allele represented in the human reference assembly contains 12 copies. Multiple transcript variants encoding different isoforms have been found for this gene.