 Normal gastric mucus expresses the mucins MUC1, MUC5AC and MUC6 Carrato C et al, Gastroenterology 1994;107:160-72. The development of gastric carcinoma is associated with changes in mucin expression, namely a decrease in MUC5AC and MUC6 and aberrant de novo expression of other MUCs Ho SB et al, Cancer Res 1995;55:2681-90. Helicobacter pylori infection induces a wide range of changes in the gastric mucus. There is a reversible alteration of mucus glycosylation, which affects the protective function of the gastric mucins Ota H et al, Virchows Arch 1998;433:419-26. 