TNF-α induces ATX expression and secretion selectively in hepatoma cell lines Hep3B and Huh7. A. Effect of TNF-α on the expression of ATX. Serum starved cells were treated with or without TNF-α (10 ng/ml) for 16 hours. Results are the mean ± SD from three QRT-PCR experiments. **, P < 0.01. B. Starved Hep3B or Huh7 cells were treated with TNF-α (10 ng/ml) for 20 hours. Cell culture medium and cell lysates were collected. 15 μg cell lysate were used for immunoblot analysis. IB indicates immunoblot.