Cover photograph (Copyright © 2016. American Society for Microbiology. All rights reserved.) PTF1A maintains pancreatic acinar cell identity. Mature acinar cells depleted of PTF1A were lineage traced by tamoxifen-induced CreER-mediated recombination of the ROSA–CAG-LSL-tdTomato locus in Ptf1a^CreER/flox mice. Cell type expression of tdTomato was determined by coimmunofluorescent staining for Tomato (red; nuclear and cytoplasmic), acinar carboxypeptidase A1 (blue; cytoplasmic), and ductal cytokeratin 19 (green) in pancreas 14 days after tamoxifen initiation. Following PTF1A depletion, acinar cells shrink, lose the digestive enzyme CPA1, and elevate CK19 to a level that is characteristic of pancreatic duct cells. (See related article on p. 3033.)