Sodium arsenite

K562 and TF-1 human erythroleukemia and Jurkat human T-cell leukemia cells were purchased from the American Type Culture Collection (ATCC, Manassas, VA). They were cultured in RPMI 1640 medium containing 10% fetal bovine serum (FBS; Mediatech, Herndon, VA), 25 mM 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, 2 mM l-glutamine, and 4.5 g/l glucose. Jurkat and TF-1 culture media contained 1 mM sodium pyruvate, and TF-1 cells were cultured in the presence of 2 ng/ml granulocyte-macrophage colony-stimulating factor. SH-SY5Y human neuroblastoma cells were also purchased from ATCC. They were cultured in 1:1 mixture of MEM with nonessential amino acids and Ham's F12 medium containing 10% FBS. They were maintained at 37°C in a humidified 95% air, 5% carbon dioxide incubator. For K562 erythroid differentiation, exponentially growing cells were exposed to hemin (Fluka-Sigma-Aldrich, St. Louis, MO). hemin and sodium arsenite (Thermo Fisher Scientific, Waltham, MA) were dissolved in 100 μM NaOH and distilled water, respectively. t-BHQ (Sigma-Aldrich, St. Louis, MO) was dissolved in dimethyl sulfoxide for 1 M solution and further diluted to 10 mM with distilled water before addition to the culture media. Sulforaphane (Sigma-Aldrich) was also dissolved in dimethyl sulfoxide for 100 mM solution.