IPMN can be classified into 4 subtypes (gastric, intestinal, pancreatobiliary, and oncocytic types) based on morphological features and immunohistochemistry for mucin core proteins (MUCs).[2] MUC1 is a membrane-associated mucin that is known to contribute to epithelial cell-to-cell interactions and is predominantly expressed in the normal pancreas. The gene discussed is MUC5AC; the disease is pancreatic intraductal papillary-mucinous neoplasm.