FIGURE 6.

Global, cytosolic, and plasma membrane-associated basal cAMP concentrations. A, comparison of basal global cAMP levels in the three cell types as measured by RIA. B and C, the basal FRET over donor ratio (R₀) for cells transduced with cytEpac2 (B) or pmEpac2 (C) was calculated to determine the relative basal cAMP concentrations. A decrease in R₀ reflects an increase in cAMP. Data were analyzed using the unpaired t test; ***, p < 0.0001. The graphs report the mean ± S.E. of three or more separate experiments. Error bars, S.E.