PTGS2 and pancreatic intraductal papillary-mucinous neoplasm: Beyond proinflammatory mediators such as COX-2-derived prostaglandins, cytokines and growth factors that are probably activated by Ras, and that may also lead to further Ras activation, have yet to be defined in more detail for the IPMN-PDAC sequence as has been done for the PanIN-PDAC sequence7.