(a–b) Examples of NPY-tdmOrange2 exocytosis events in β-cells from Epac2-/- mice or from wildtype littermates, stimulated with 75 mM K+ in presence of forskolin. Note absence of a flash in Epac2 ko. (c) Fraction of flash events for experiments in (a–b); differences are significant in absence (p=0.027, Kruskal Wallis/Dunn test) or presence of fsk (p=0.011). Number of mice: 4 (WT); 4 (Epac2 KO); 5 (WT + fsk); 2 (Epac2 KO + fsk). n, number of cells. (d) Cumulative exocytosis for experiments in absence of forskolin (a,c left) for wildtype (black) and Epac2-/- cells (red), differences are n.s. (e) Cumulative exocytosis for experiments in presence of forskolin (b,c right) for wildtype (black) and Epac2-/- cells (red). p=0.003, Kruskal Wallis/Dunn test. (f–g) Cumulative frequency histograms and medians (inset) of NPY release times for exocytotic events in d (no forskolin, 23 events for wt, 22 for Epac2-/-) and E (with forskolin, 50 events for wt, nine for Epac2-/-). Differences in f are significant (p=0.043; Kolmogorov-Smirnov test).