Reversing effects of thiol-containing agents on the actions of celastrol in U937. Cells were seeded at 2 × 105/ml in a 24-well plate. After being pre-treated with 2 mM NAC, 0.1 mM Vit C, 2 mM GSH or 2 mM GSSG for 1 h, cells were exposed to 600 nM celastrol for 1 d. At the end of the indicated time points, cells were analysed for cell cycle location and protein detection by FCM. A: Flow cytometric histogram of HSP70 expressions in U937 with various treatments. B: Cell cycle distributions of drug treated U937. The dark gray, light gray and white areas in the circle track represent the ratio of cells at G0/G1, S, and G2/M phases, respectively. C: Expressions of selected proteins in U937 with different pre-treatments. The vertical axis represents the relative levels of each protein, which were determined by dividing individual protein intensity by its levels in the DMSO-treated sample. The DMSO-control sample was set at 1.0. The plotted data represents the mean results of three repetitions. The values under the figure are mean ± SD for each sample. * P < 0.05, **P < 0.01 when compared with DMSO-control.