cAMP does not affect granule migration. 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. Treatments with different concentrations of extracellular Ca²⁺ and with FSK are indicated by bars at the top of each graph. The open, black, and gray bars indicate 0 mM Ca²⁺ (0 Ca²⁺), 2 mM Ca²⁺ (2 Ca²⁺), and 1 μM FSK, respectively. (A and C) Mean time course of intensity of granules (A, N = 24, and C, N = 10, black line) approaching to the plasma membrane during an increase in [Ca²⁺]_i (A, n = 13, and C, n = 11, green line) in the absence (A) or presence (C) of 1 μM FSK. (B) Mean time course of intensity change of granules (black line) and [Ca²⁺]_i (green line) after the FSK treatment (n = 11). (D) Mean time course of return of granule intensity after Ca²⁺ removal. The black and red lines indicate kinetics of granule moving away from the plasma membrane in the absence or presence of FSK, respectively. [Ca²⁺]_i level is shown as green dotted line without FSK and green solid line with FSK. (E) Number of granules near the plasma membrane under the conditions 0 Ca²⁺, 2 Ca²⁺ (n = 23), FSK + 0 Ca²⁺ (n = 9), and FSK + 2 Ca²⁺ (n = 9), normalized to that in 0 Ca²⁺ in each experiment.