Cre expression was capable of causing IPMN by forced expression of HER2NT alone, whereas Ptf1a-Cre, which is expressed at E9.529, did not cause IPMN lesion development, suggesting that the cell type or duration of Cre expression is strongly associated with the development of IPMN. This evidence concerns the gene PTF1A and pancreatic intraductal papillary-mucinous neoplasm.