Multifunctionality is one of the ubiquitous properties of biological
macromolecules and is also a feature of the gel-forming and soluble secreted mucin
glycoproteins. These mucin molecules participate in various basic cell processes in both
physiological and pathological conditions. Their functions appear to be important both for
embryonic/fetal development and for adult cells and tissues. They perform such functions
as lubrication and hydration of mucosal surfaces, defending them against mechanical and
chemical harm and infection. The gel-forming mucins have the potential to modify and
catalyze organic chemical reactions. The secreted glycoproteins are active participants in
innate immunity. Depending on cell type and type of neoplasm, gel-forming mucins
function as tumor suppressors or tumor promoters. The secreted mucins possess
antibacterial, antifungal and antiviral activities. In addition, the important processes of
biological reproduction are also regulated by mucins, in particular by the soluble
MUC9/OGP mucin glycoprotein. This chapter presents the data on the multifunctional
potentials of the secreted mucins as regulators of cell functions.
Keywords: Overt functions, secreted mucins, multifunctional potential.
