A. Immunoblotting of membrane fractions from cells harboring the plasmids overproducing the indicated transporters. The respective outer membrane channels (OMF) are tagged with a C-terminal His-tag and visualized with anti-His monoclonal antibody. B and C. Effect of IPTG inducer concentration on MICs of ciprofloxacin in PΔ4 (B) and PΔ4-Pore (C) cells expressing indicated transporters. D and E. PΔ4 (D) or PΔ4-Pore (E) cells harboring either pMexHI-OpmD, pMexGHI-OpmD, or pMexEF-OprN are tested against a library of FQ. Fold changes in MICs are shown for cells carrying different plasmid constructs are shown. FQ for each ratio are listed from bottom to top: Ciprofloxacin, Enrofloxacin, Levofloxacin, Gatifloxacin, Moxifloxacin, Prulifloxacin, Sparfloxacin, Difloxacin, Lomefloxacin, Ofloxacin, Pazufloxacin, Norfloxacin, Pefloxacin, Sarafloxacin, and Nadifloxacin.