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. 2013 Feb 14;8(2):e56666. doi: 10.1371/journal.pone.0056666

Figure 1. Berberine down-regulates EGFR level and activates Cbl in colon tumor cells.

Figure 1

(A) cells were cultured in serum-starved RPMI 1640 medium at 37°C (non-permissive condition) for 24 hours with or without berberine at 50 µM treatment for indicated times from the end of the experiment. Cellular lysates were collected for Western blot analysis to detect indicated signaling pathways. (B) cells were treated with berberine at 50 µM under non-permissive condition for 18 hours in the presence or absence of EGF (30 ng/ml) treatment for 5 minutes. 1 mg of cellular lysates were prepared for immunoprecipitation using an anti-EGFR antibody. EGFR and co-immunoprecipated proteins were analyzed using Western blot analysis. The β-actin blot was used as a protein loading control. (C) mRNA was isolated from cells cultured under non-permissive condition for 24 hours with or without berberine at 50 µM treatment for indicated times from the end of the experiment. Real-time PCR analysis was performed to detect the EGFR mRNA level. The EGFR mRNA expression level in the control group was set as 100%, and mRNA expression levels in treated groups were compared to the control group. Data in this Figure are representative of three separate experiments.