Treatment with proteasome inhibitor bortezomib decreases organic anion transporting polypeptide (OATP) 1B3-mediated transport in a substrate-dependent manner
pCMV6-FLAG-OATP1B1 (A) or pCMV6-FLAG-OATP1B3 (B) vectors were transfected into HEK293 cells, either alone or in combination with HA-Ub expression vector. Transfection with empty vector pCMV6 served as the vehicle control in all experiments. Whole cell lysates (WCL) were subjected to immunoprecipitation (IP) with HA or FLAG antibody, followed by immunoblotting (IB) with FLAG or HA antibody, respectively. After stripping, the same blot was re-probed with HA or FLAG antibody, as indicated in the figure. Immunoblots of HA and FLAG were also conducted using WCL with β-actin serving as the loading control. Representative immunoblot images from n = 3 independent experiments are shown.