Fig 1.

Effect of quinolones on OPN release. A549 cells were plated at 1 × 10⁴ in 96-well plates, and after 24 h, the cells were washed twice with serum-free medium. Fresh serum-free medium and drugs at final concentrations of 1, 3, 10, and 30 μg/ml were added. The cells were incubated for a further 48 h, and the OPN concentrations in the cell culture supernatant were measured by ELISA, as described in Materials and Methods. OPN secretion was normalized by the cell viability optical density (570 to 630 nm) value of the MTT assay and expressed as percent increase above control. Controls are the wells treated only with solvent. The results are expressed as means ± SDs. Representative data of three independent experiments are shown. ***, P < 0.001 compared to the control; **, P < 0.01 compared to the control; *, P < 0.05 compared to the control.