GO-203 treatment decreases NADPH and GSH levels. (A-D) U266 (A,C) and RPMI8226 (B,D) cells were left untreated, and treated with 5μM GO-203 or 5μM CP-2 each day for 3 days. The U266 (A) and RPMI8226 (B) cells were analyzed for NADPH levels on day 3. The results are expressed as the NADPH level (mean ± SD of 3 determinations). The U266 (C) and RPMI8226 (D) cells were also analyzed for GSH levels (mean ± SD of 3 determinations) at the indicated times.