Protective effect of CMZ against APAP-induced change in cell morphology, cell death rate and the reduction of p53 and p21. (A) C6 glioma cells were pretreated with 20 μM CMZ for 16 h before APAP was treated for additional 24 h in the absence and presence of CMZ. Cell morphology, treated differently as indicated, was then determined under light microscopy (magnification, x 200). (B) CYP2E1 activity was determined by N-nitrosodimethylamine demethylase (Bae et al., 2001) with and without CMZ treatment. Each bar represents the average ± SD from three independent experiments. *, P < 0.01, significantly different from the DMSO-treated control. (C) Immunoblot analyses of p53, p21, and actin. The soluble fraction (100 μg/well) from C6 cells treated with APAP in the absence and presence of CMZ were subjected to 12% SDS-PAGE followed by immunoblot analysis using the respective antibody against p53 (top), p21 (middle), or actin (bottom).