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. Author manuscript; available in PMC: 2009 Oct 1.

Published in final edited form as: J Cell Biochem. 2008 Oct 1;105(2):585–595. doi: 10.1002/jcb.21859

Fig. 3 — Quercetin induces ubiquitination of Her-2/neu and concomitantly enhances the recruitment of Hsp90 to Her-2/neu. A: SK-Br3 cells were cotreated with 200 μM of quercetin and MG-132 (5 μM) or NH₄Cl (10 mM) for 24 hr. Cell extract was prepared by resuspending in lysis buffer (NP-40 soluble) and the insoluble proteins were extracted with SDS sample buffer and then boiled (NP-40 insoluble). Her-2/neu protein level was compared by Western blot analysis. B: SK-Br3 cells were treated with 200 μM of quercetin for the indicated times After Her-2/neu proteins were immunoprecipitated, ubiquitination level and interacting amount of Hsp90 were compared by Western blot analysis. C: SK-Br3 cells were treated with increased amounts of quercetin for 4 h and then analysed as above. D: SK-Br3 cells were either left untreated or treated with 200 μM of quercetin for 4 h and then whole cell lysate was prepared. After immunoprecipitation with normal mouse serum, anti-EGFR, or anti-Her-2/neu antibody, the ubiquitination level and interacting amount of Hsp90 were compared by Western blot analysis.

Fig. 3 — Quercetin induces ubiquitination of Her-2/neu and concomitantly enhances the recruitment of Hsp90 to Her-2/neu. A: SK-Br3 cells were cotreated with 200 μM of quercetin and MG-132 (5 μM) or NH₄Cl (10 mM) for 24 hr. Cell extract was prepared by resuspending in lysis buffer (NP-40 soluble) and the insoluble proteins were extracted with SDS sample buffer and then boiled (NP-40 insoluble). Her-2/neu protein level was compared by Western blot analysis. B: SK-Br3 cells were treated with 200 μM of quercetin for the indicated times After Her-2/neu proteins were immunoprecipitated, ubiquitination level and interacting amount of Hsp90 were compared by Western blot analysis. C: SK-Br3 cells were treated with increased amounts of quercetin for 4 h and then analysed as above. D: SK-Br3 cells were either left untreated or treated with 200 μM of quercetin for 4 h and then whole cell lysate was prepared. After immunoprecipitation with normal mouse serum, anti-EGFR, or anti-Her-2/neu antibody, the ubiquitination level and interacting amount of Hsp90 were compared by Western blot analysis.