In vivo effects of rosiglitazone in ob/ob mice. Rosiglitazone (R) (10 mg/kg, once a day) was administered orally to ob/ob mice (9 weeks old, male) for 2 weeks. Plasma glucose concentrations (A) and body weights (B) were determined weekly. Fat tissues were isolated after 2 weeks of administration, and protein expression was determined by Western blotting (C and D) and by immunoprecipitation with anti-polyubiquitination antibody followed by Western blotting (E). V, vehicle; R, rosiglitazone. Experiments were conducted three times, and representative results are shown. Densitometric analysis was conducted using UN-SCAN-IT Gel version 5.1 software (Silk Scientific). *, p < 0.05; **, p < 0.01 versus vehicle controls.