(B) MDCK cells transfected with GFP-TM5b or GFP (green) were treated without (top) or with (bottom) forskolin and labeled for F-actin (red). (C and D) Quantification of F-actin associated with the apical membrane. (C) MDCK cells transfected with TM5b siRNA or control siRNA were treated with or without forskolin and biotinylated on the apical surface. The lysates were incubated with phalloidin conjugated with Alexa Fluor 488 and precipitated with streptavidin-agarose beads and the fluorescence was measured. Each value was normalized to control siRNA-transfected cells without forskolin. Data represent the mean and SE from three independent experiments. *, P < 0.05 versus control siRNA-transfected cells without forskolin. (D) MDCK cells transfected with GFP-TM5b or GFP were treated with or without forskolin and biotinylated on the apical surface. The lysates were incubated with phalloidin conjugated with Alexa Fluor 568 and precipitated with streptavidin-agarose beads and the fluorescence was measured. Each value was normalized to GFP-transfected cells without forskolin. Data represent the mean and SE from three independent experiments. *, P < 0.05 versus GFP-transfected cells without forskolin; **, P < 0.05 versus GFP-transfected cells with forskolin.Copyright information:Taken from "Reciprocal interaction with G-actin and tropomyosin is essential for aquaporin-2 trafficking"The Journal of Cell Biology 2008;182(3):587-601.Published online 11 Aug 2008PMCID:PMC2500142.