Mucin 13 is a 512aa hemopoietic transmembrane mucin belonging to a family of secreted and cell surface glycoproteins and may play a role in cell signaling. It contains a serine/threonine-rich mucin repeat domain predicted to be heavily O-glycosylated, three cysteine-rich EGF-like domains, a SEA domain and also has sites for N-glycosylation and phosphorylation. Activation of NF-kappa-B signaling pathway by the inflammatory cytokines TNF-alpha and TGF-beta leads to upregulation of Mucin 13. It is a homodimer of beta subunits and is highly expressed in epithelial tissues, gastrointestinal and respiratory tracts, kidney, small intestine, appendix and stomach. RT-PCR and immunoblot analysis supports the up regulation of Mucin 13 in gastric cancers and is usually present on the apical side of tubular glands in intestinal-type cancers and in the cytoplasm in diffuse cancers.