MUC5AC and neoplasm: Mucin-type O-linked carbohydrates may constitute up to 80% of the total mass of these glycoproteins (Clausen and Bennett, 1996); O-glycosylation has been shown to be important in the binding of cell adhesion molecules, cell differentiation, invasion, and metastasis in tumours (Nakamori et al, 1994; Clausen and Bennett, 1996; Sutherlin et al, 1997; Nomoto et al, 1999).