Wild-type AQP2, but not S256A mutant AQP2, accumulates at the plasma membrane in the presence of CT. Indirect immunofluorescence microscopy of AQP2 staining in LLC-AQP2 wild type and S256A mutant expressing cells incubated in the presence or absence of CT. The AQP2 (S256A) mutant is located on intracellular vesicles similar to wild type AQP2 in basal conditions (A and C, respectively). After CT treatment (100 nM, 10 minutes) AQP2 wild type accumulates at the plasma membrane (B), whereas localization of the AQP2 (S256A) mutant is unchanged (D). These images are representative of three independent experiments. The bar indicates 10 μm.