As₂O₃ activates caspases and restores cellular levels of GSH in MRL/lpr mice. (A) Activated caspase-2 (black bars), -8 (white bars), and -9 (gray bars) were detected by flow cytometry in the spleen-cell subpopulations of 4-month-old MRL/lpr mice (4/group) that had been treated daily for 4 days with As₂O₃ (5 μg/g). (B) Intracellular levels of GSH were detected by flow cytometry in the spleen-cell populations of 4-month-old MRL^+/+ and MRL/lpr mice (5/group) that had been treated daily for 4 days with As₂O₃ (5 μg/g; ▪) or PBS (□). Error bars indicate SE.