CBY1 and exocrine pancreatic insufficiency: In an effort to understand the mechanistic basis of the exocrine pancreatic insufficiency in Cby1-KO mice, we went on to investigate early changes in acinar cells by visualizing zymogen granule (ZG) distribution using the lectin peanut agglutinin (PNA), which has been shown to detect apical zymogen granules45,46.