This study showed that deletion of Jag1 accelerated KrasG12D-mediated ADM and PanIN development, and that expression level of Jag1 dictates the progression of preneoplastic lesions in the pancreas: complete and partial loss of Jag1 resulted in SCN-like and IPMN-like cystic neoplasms, respectively, whereas retained Jag1 expression led to the progression into PDAC. This evidence concerns the gene JAG1 and severe congenital neutropenia.