Fig. 3.
Dose-dependent proteasome inhibition by flavonoids. A. HL60 cells were treated with DMSO or 1, 25, or 50 μM of the indicated flavonoids for 24 h. Chymotrypsin-like activity is represented as a percentage of the solvent (DMSO) control. B. Western blot analysis was performed using reserved aliquots from the chymotrypsin-like activity assay. A ubiquitinated form of IκBα was observed at approximately 56 kD and is indicated by an arrow. Actin was used as a loading control. Error bars, SD; *, p-value < 0.05; **, p-value < 0.01.