The effect of Sgk1 on OAT3 ubiquitination. a. Top panel: COS-7 cells were transfected with hOAT3, Nedd4-2 and control vector or with hOAT3, Nedd4-2 and CA-sgk1. Transfected cells were treated with the PKC activator PMA (1 μM) for 30 min to enhance hOAT3 ubiquitination. Treated cells were then lysed and hOAT3 was immunoprecipitated by anti-myc antibody (epitope myc was tagged to hOAT3), followed by immunoblotting with anti-ubiquitin antibody. Bottom panel: The same immunoblot from Fig. 8a, Top panel was reprobed by anti-myc antibody. b. Densitometry plot of results from Fig. 8a, top panel as well as from other experiments. The values are mean ± S.E. (n = 3).