The present invention provides inhibitors of mucin-type O-linked
glycosylation, and in particular inhibitors of polypeptide
N-acetyl-.alpha.-galactosaminyltransferases; as well as compositions
comprising the inhibitors. The present invention further provides methods
of identifying inhibitors of polypeptide
N-acetyl-.alpha.-galactosaminyltransferases. The inhibitors are useful in
various applications, including research applications, and treatment
methods.