STAT3 was constitutively activated in A549 human lung cancer cell line and the efficiency of STAT3 decoy ODN transfected into A549 cells. (A) The A549 lung cancer cells were lysed in lysing buffer and the whole cell extracts (30 μg/lane) were separated by SDS-PAGE and then examined by western blotting using anti-STAT3, anti-phospho-specific STAT3 (Tyr 705, Ser727) or β-actin antibodies. The proteins were then detected by the enhanced chemiluminescence (ECL) system by exposing to X-ray film. (B) A549 cells were transfected with FITC-labeled STAT3 decoy ODN at final concentration of 12.5, 25 and 50 nmol/L in presence of lipofectamine 2000. After transfected for 6 h, the cells were examined by flow cytometry. (C) After transfected with 25 nmol/L FITC-labeled STAT3-ODN for 6 h, the cells were fixed, permeabilizated and stained with DAPI, and then fluorescent microscopy was used to observe the nucleus location of ODN. STAT3 decoy ODN (green) and nuclei (blue) were overlaid with their contrast image.