GO-203 treatment decreases NADPH and GSH levels. (A-D) HuT78 and H9 cells were left untreated and treated with 5 μM GO-203 or 5 μM CP-2 each day for 3 days. The HuT78 (A) and H9 (C) cells were analyzed for NADPH levels on day 3. The results are expressed as the NADPH level (mean ± SD of 3 determinations). The HuT-78 (B) and H9 (D) cells were also analyzed for GSH levels (mean ± SD of 3 determinations) on day 3.