MUC4 (Mucin 4, Cell Surface Associated) is a Protein Coding gene. Among its related pathways are O-linked glycosylation and HIV Life Cycle. The major constituents of mucus, the viscous secretion that covers epithelial surfaces such as those in the trachea, colon, and cervix, are highly glycosylated proteins called mucins. These glycoproteins play important roles in the protection of the epithelial cells and have been implicated in epithelial renewal and differentiation. MUC4 encodes an integral membrane glycoprotein found on the cell surface, although secreted isoforms may exist. At least two dozen transcript variants of MUC4 have been found, although for many of them the full-length transcript has not been determined or they are found only in tumor tissues. MUC4 contains a region in the coding sequence which has a variable number (>100) of 48 nt tandem repeats.
