Muc1 localization within acinar structures. (A-F) Immunofluorescence of dissociated wildtype acini for Muc1 (green), amylase (red) and DAPI (blue). Muc1 is detected within small clusters of amylase+ acinar cells as well as in single amylase+ cells, suggesting that these cells, as well as ducts, express the Muc1 gene. (G-I) Confocal z-projection (0.75 μm) of adult wildtype pancreas, wholemount stained for Muc1 (green), E-cadherin (red) and DAPI (blue). Outline in I indicates a single acinar unit, with a shared central lumen. Membrane-bound Muc1 protein localizes to this central lumen (open arrowhead), as well as extending between two individual acinar cells (closed arrowhead). Note that there appears to be no centroacinar cell in this cluster, the lumen of which is entirely defined by the apical surfaces of adjacent acinar cells, and coated by Muc1 protein. Scale bars: 10 μm.