Figure 4. Effect of immunoproteasome inhibitors on CYP2B down-regulation elicited by IL-1.

Hepatocytes (3 days old) were pretreated with 1 mM PB, which was present for the rest of the experiment. After 2 days of PB induction, the cells were treated with IL-1 (5 ng/ml) or control medium. After 6 h, proteasome inhibitors (10 μM) or vehicle were added without medium change, and the cells were harvested after a further 18 h of incubation. (A) Structures of the immunoproteasome inhibitors. (B) Western blots of cell lysates. (C) Quantification of the CYP2B Western blot. Results are means±S.E.M. a, significantly different from control; b, significantly different from IL-1-treated cells, P<0.05, one-way ANOVA and Tukey's test.