FIG. 6.

Inhibition of p38 activity does not markedly affect LMP1 RNA levels in the absence of RNA synthesis. Estrogen-starved cells were induced with estrogen for 3 h. The cells were then treated with DRB alone (100 μM dissolved in DMSO), DRB and the p38 inhibitor SB203580.HCl (80 μM dissolved in dH₂O), or just DMSO as a control. Samples were collected at the times indicated in the figure and subjected to quantitative RT-PCR and immunoblot analysis. The LMP1 RNA level was normalized against GAPDH RNA. The results shown are the means of four independent experiments, and the T bars indicate the standard errors of the means. The asterisks indicate statistical significance in differences relati7ve to the corresponding DRB samples, obtained by a two-tailed paired t test. Immunoblot analysis was used to detect phosphorylated p38 (P-p38), LMP1, and GAPDH protein levels in the cells. Equal protein loading was confirmed by monitoring the GAPDH levels.