β-galactosidase enzyme assay on Hep3B_{EGFP-AQP9/β-gal} cells. Hep3B_{EGFP-AQP9/β-gal} cells exhibited an increase in As₂O₃ sensitivity compared with Hep3B_EGFP/β-gal cells (Student t test for each of the points analyzed). Note that the difference in As₂O₃ sensitivity remained comparable with increasing concentrations of As₂O₃.