This gene encodes a membrane-bound protein that is a member of the mucin family. Mucins are O-glycosylated proteins that play an essential role in forming protective mucous barriers on epithelial surfaces. These proteins also play a role in intracellular signaling. This protein is expressed on the apical surface of epithelial cells that line the mucosal surfaces of many different tissues including lung, breast stomach and pancreas. This protein is proteolytically cleaved into alpha and beta subunits that form a heterodimeric complex. Diseases associated with MUC1 include Tubulointerstitial Kidney Disease, Autosomal Dominant, 2 and Autosomal Dominant Tubulointerstitial Kidney Disease. Among its related pathways are Cell adhesion_Cell-matrix glycoconjugates and Bacterial infections in CF airways.