Fig. 2. Quantitative analysis of the effect of EP₃ receptor stimulation on the localization of AQP2 in IMCD cells. IMCD cells were treated as indicated in the legend to Fig. 1. AQP2 immunofluorescence signals were detected by laser scanning microscopy. The intracellular and plasma membrane fluorescence signal intensities were determined and related to nuclear signal intensities. Ratios of intracellular/plasma membrane signal intensities were calculated (n20 cells for each condition tested; mean ± s.e.; three independent experiments). Ratios >1 indicate a mainly intracellular distribution of AQP2, and ratios <1 indicate a predominant localization at the plasma membrane. *, values significantly different from untreated control cells (P<0.001).