Effects of vitamin E on As₂O₃/DHA-mediated cytotoxicity. Cells were treated for 48 hours with 1 μM As₂O₃ and 25 μM DHA in combination or left untreated (control). To demonstrate the blocking effect of vitamin E on As₂O₃/DHA-mediated cytotoxicity, 20 μM vitamin E was added to the cultures simultaneously with As₂O₃ and DHA. Cell viability was determined by means of the colorimetric EZ4U viability assay. Values represent the mean (± SD) of 3 independent experiments.