cAMP does not affect granule mobility. Before each experiment, cells were preincubated with 1 μM ionomycin for at least 5 min in Ca²⁺-free solution (0 Ca²⁺), and all test solutions contained 1 μM ionomycin in a Ca²⁺-free solution. Average speed of granule movement during treatment with (A) 2 mM Ca²⁺ (‘2 Ca²⁺’, n = 2, n = 19), (B) 1 μM FSK (n = 3, n = 30), and (C) 2 mM Ca²⁺ with FSK (n = 3, n = 25), where N and n indicate the number of cells and granules for each experiment. External Ca²⁺ concentration was exchanged from 0 to 2 mM Ca²⁺ to increase [Ca²⁺]_i. Red dotted lines indicate average granule speed in control conditions before external Ca²⁺ or FSK treatments. Average MSD of the same granules is plotted on the right side of each figure. The same color coding for the treatments is used.