Immunofluorescence of EmGFP-FPN1–transfected and Salmonella infected Nos2 wild-type and Nos2^−/− PE-MΦ. (A and B) Nos2 wild-type (A) and Nos2^−/− (B) PE-MΦ were transfected with the N-terminal EmGFP-FPN1 construct (right) or empty plasmid (left). Subsequently, cells were infected with S. typhimurium for 16 h. The number of intracellular bacteria was determined by immunofluorescence and is depicted as a function of GFP expression as in Fig. 6 (n = 4 independent experiments). (C–F) Representative images acquired at 1,000× magnification are depicted. (left) GFP in green; (middle) CSA1/S. typhimurium in red; (right) DAPI/nuclei in blue. The cell membrane and the number of intracellular bacteria are indicated. Bars, 20 µm. (C and D) Nos2 wild-type PE-MΦ were transiently transfected with empty EmGFP N-terminal plasmid (C) or a FPN1-EmGFP N-terminal construct (D), respectively. (E and F) Nos2^−/− PE-MΦ were transiently transfected with empty EmGFP N-terminal plasmid (E) or a FPN1-EmGFP N-terminal construct (F), respectively. **, P < 0.01; ***, P < 0.001.