Ca²⁺ increases in acinar cells of both strains at a higher concentration of cholecystokinin.

A, C. Cross-sectional fluorescence images of wild-type (WT; A) and knockout (KO; C) acini loaded with fura-2 FF-AM. B. Time course of changes in [Ca²⁺]_i in apical (red box in A) and basal (blue box in A) regions of a WT acinar cell during application of 1 nM cholecystokinin (CCK). D. Time course of changes in [Ca²⁺]_i in apical (red box in C) and basal (blue box in C) regions of a KO acinar cell during application of the same concentration of CCK as in B.