Fig. 1. F-actin and IP₃Rs are both contained within the apical subplasmalemmal compartment of pancreatic acini. Isolated pancreatic acinar cell clusters were fixed and stained with (A) phalloidin to highlight F-actin, or with (B) antibodies to IP₃R2 (pAb) and IP₃R3 (mAb). The image in A is a confocal section taken through the middle of the cell cluster. The images in B are 10 confocal serial sections separated by approximately 1 µm in the z-axis projected onto a single plane. Arrows denote the apical membrane and arrowheads denote the basolateral membrane. Bar, 10 µm.