Figure 6.

Effect of R-roscovitine on protein phosphatase expression and activity in MDCK-hAQP2 cells. (A) Immunoblotting expression studies of protein phosphatases PP1, PP2A, and PP2B in MDCK-hAQP2 cells. Equal amounts of proteins from MDCK-hAQP2 cells left untreated (CTR) or incubated with R-roscovitine (R) were subjected to electrophoresis and immunoblotted using specific antibodies as described in Concise Methods. Immunoreactive signals were semiquantified by densitometry (right panel), indicating that R-roscovitine reduces only PP2A protein content. (B) Protein phosphatase activities were evaluated using an immunoprecitation assay kit as described in Concise Methods. Data (means±SEMs; *P<0.05) indicate that R-roscovitine decreases PP2A activity only.