Anti-MUC4 (Mucin 4 / Gastric Mucin) Monoclonal Antibody (Clone: MUC4/3105)

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. This gene encodes an integral membrane glycoprotein found on the cell surface, althoµgh secreted isoforms may exist. MUC-4 transcripts have been detected in normal respiratory epithelium and lung. MUC-4 is a very specific (100%) and sensitive (90%) marker of lung adenocarcinomas and is negative for mesotheliomas. Reportedly, MUC-4 expression in invasive ductal carcinoma of the pancreas is an independent factor for poor prognosis. Protein function: May play a role in tumor progression. Ability to promote tumor growth may be mainly due to repression of apoptosis as opposed to proliferation. Has anti-adhesive properties. Seems to alter cellular behavior through both anti-adhesive effects on cell-cell and cell- extracellular matrix interactions and in its ability to act as an intramembrane ligand for ERBB2. Plays an important role in cell proliferation and differentiation of epithelial cells by inducing specific phosphorylation of ERBB2. The MUC4-ERBB2 complex causes site- specific phosphorylation of the ERBB2 'Tyr-1248'. In polarized epithelial cells segregates ERBB2 and other ERBB receptors and prevents ERBB2 from acting as a coreceptor. The interaction with ERBB2 leads to enhanced expression of CDKN1B. The formation of a MUC4-ERBB2-ERBB3-NRG1 complex leads to down-regulation of CDKN1B, resulting in repression of apoptosis and stimulation of proliferation. [The UniProt Consortium]