Three day-old hepatocytes were pretreated with 1 mM PB, which was present for the rest of the experiment. After two days of PB induction, the cells were treated with NOC-18 (500 µM) or control medium with or without the indicated proteasome inhibitors. The cells were harvested after a further 24 h of incubation. (A) Western blots of cell lysates. (C) Quantitation of CYP2B Western blot. a, significantly different from control; b, Significantly different from IL-1-treated cells, P<0.05, one-way ANOVA and Tukey’s test.