Involved in epithelial cell protection, adhesion modulation, and signaling. May be involved in epithelial cell growth regulation. Stimulated by both cytokine TNF-alpha and TGF-beta in intestinal epithelium. Ubiquitous, with higher expression in colon. Down-regulated in colorectal cancer as well as in the colon of patients with ulcerative colitis (UC) and Crohn's disease (CD). By listeriolysin O. The proteolytic cleavage occurs within the SEA domain. This domain is not interchangeable, suggesting that it is insufficient to mediate efficient cleavage. Infection by L.monocytogenes induces increases in mucin secretion and MUC4 and MUC12 transcription. This may constitute a host cell defense response that inhibits the entry of listeria monocytogenes in the cell.