Inhibitory effect of STAT3 decoy ODN on A549 lung cancer cells in vitro. (A) A549 cells were seeded at a density of 1 × 104 cells per well in 48 well plates. After 24 h, the cells were treated with 25 nmol/L STAT3 decoy ODN, STAT3 scramble ODN or vehicle control (TE) for different time using lipofectamine 2000. The cumulative number of cells was accounted using trypan blue exclusion. Values are expressed as mean ± SD of three independent experiments. (B) A549 cells (4 × 104/well) were treated with STAT3 decoy ODN or scramble decoy ODN for 18 hours at 37°C, and then pulsed with [3H]-thymidine for an additional 6 hours. The incorporation of [3H]-thymidine was analyzed by liquid scintillation counting. (C) A549 cells were plated in six well plate, after transfected with 25 nmol/L STAT3 decoy ODN or scramble ODN, the apoptotic A549 cells were detected by flow cytometry using Annexin V-FITC and PI. The histogram represented the percentage of apoptotic cells. Values are expressed as the mean ± SD of three independent experiments. Statistical significance was determined as *p < 0.01 compared to other groups.