In intestinal type tumours, cancer cells exhibit an aberrant mucin expression pattern characterized by a decrease in the levels of the gastric mucins MUC5AC and MUC6 and the concomitant upregulation of genes codifying for intestinal mucins, including the de novo expression of MUC2, as well as abnormally elevated levels of expression of MUC3, MUC4 and MUC5B [11,13,14,90,92,93,94]. The gene discussed is MUC3A; the disease is cancer.