Munc18c depletion reduces supraphysiologic CCK-evoked basolateral PM exocytosis. Ad–syncollin-pHluorin–infected WT and Munc18c+/− acini were stimulated with maximal (100 pm) or supramaximal (10 nm) CCK-8 and images were recorded by spinning disk microscopy. A and B, left panels show representative images of WT (top) and Munc18c+/− (bottom) acini at indicated time points after stimulation with 100 pm CCK-8 (A) or 10 nm CCK-8 (B). Scattered plots on right panels are the quantitative analysis (A, WT, 10 acini and Munc18c+/−, 12 acini; B, WT, 10 acini and Munc18c+/−, 12 acini; each from three independent experiments) of total fusion events and fusion events at apical and basolateral areas normalized to cell area and recording time. Apical and basolateral areas were demarcated by drawing two concentric circles on images considering the apical lumen as center (29, 36). Inner circle (A and B) that encompasses two-third area of the outer circle was designated as apical pole. The region between inner and outer circle (A and B) was considered as basolateral (29, 36, 59). Analyses were mean ± S.D. Scale bars, 10 μm. *, p < 0.05.