Abnormalities in mucin-type glycoprotein expression have been documented in a variety of cancers, identifying these molecules as targets for immunologically based therapies and prognostic/diagnostic assays. Epithelial mucin proteins are synthesized by cells lining the ducts and lumens of various epithelial surfaces and contribute to the protective and lubricating functions of mammalian mucus (1) . These proteins are characterized by a variable number of amino acid tandem repeats and extensive O-glycosylation at serine and threonine residues, resulting in a composition of 50-80% carbohydrate by weight. To date, at least 9 mucin genes, encoding the protein backbone of these glycoproteins, have been identifi ed and at least partially sequenced.
