Figure 4: Emodin and aloe-emodin decrease ERα protein levels by promoting protein degradation. (a) MCF-7 cells were treated with 25 μM of emodin or aloe-emodin for 24 h prior to quantitative real-time PCR to assess ERα mRNA expression. Data were presented as the fold change compared to control levels. The experiments were performed in triplicate, and each condition was replicated four times within each experiment. The results are presented as the mean SEM. (b, c) MCF-7 cells were treated with various concentrations of emodin or aloe-emodin in the presence of MG132 (proteasome inhibitor, 5 μM) for 24 h. ERα protein levels were detected by western blotting. β-Actin was used as an internal control.