Fig. 3.

As₂O₃-induced phosphorylation of TAO2 and TAK1 is diminished by the reducing agents DTT and NAC. A, NB4 cells were preincubated for 1 h with DTT (1 mM) and subsequently incubated with As₂O₃ (2 μM) for 30 min. Cells were then analyzed by flow cytometry for the presence of ROS as described under Materials and Methods. Data are expressed as the fold increase in mean fluorescence over untreated samples and represent the means ± S.E. of two independent experiments. B, NB4 cells were incubated with or without combinations of DTT (1 mM), NAC (10 mM), and As₂O₃ (2 μM) as indicated. Equal amounts of total cell lysates were resolved by SDS-PAGE and immunoblotted with an anti-phospho-TAO2 (Ser181) antibody (top). The same blot was reprobed with an anti-GAPDH antibody to control for protein loading (bottom). C, similar experiment as in B, demonstrating immunoblotting with an anti-phospho-TAK1 (Ser412) antibody (top).