Probable regulator of exocrine pancreas development. Expressed exclusively in the exocrine cells during pancreas development. Expressed both maternally and zygotically. Expression increases between 1 dpf and 2 dpf when the exocrine pancreas starts to develop and is highest between 2 dpf and 5 dpf. Starts to express in the pancreatic area at 33 hpf. Later in development, the strongest domain of expression appears in the pancreas. Cells expressing are located about 1 somite anterior to the cluster of preproinsulin-positive cells, just before exocrine specification begins. By 36 hpf, expressing cells start to contact the preproinsulinpositive cells as a result of gut rotation. These expressing cells continue to grow posteriorly to form a typical pancreas-like shape at 3 dpf. From 33 hpf to 3 dpf, there is no overlap between expressing cells and preproinsulinpositive cells, indicating that expression is excluded from endocrine cells. Conversely, expression completely overlaps with trypsin expression at 3 dpf. Expression is directly regulated by pancreas-specific transcription factor ptf1a. Probably also regulated by retinoic acid (RA). Impaired exocrine cell differentiation and growth. Loss or significant reduction of exocrine cells are due to lineage-specific cell cycle arrest but not apoptosis. The endocrine cell mass appear normal. Cell cycle arrest is mediated by up-regulation of cell cycle inhibitor genes cdkn1a, cdkn1b, and cyclin gccng1. Belongs to the PPDPF family.