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. 2019 Aug 8;9:743. doi: 10.3389/fonc.2019.00743

Figure 5.

Figure 5

Proteasome-dependent degradation of STA3 protein in carnosol-treated MDA-MB-231 cells. (A) Western blot analysis of STAT3 protein level in MDA-MB-231 cells pre-treated with the autophagy inhibitors 3-MA and CQ. Cells were pretreated with or without 3-MA (50 mM) and CQ (50 μM) for 1 h and then carnosol was added, and cells were further incubated for 24 h. (B) Carnosol induces proteasome-dependent degradation of STAT3. Inhibitors of the proteasomes (MG-132 and Bortezomib) restored STAT3 protein to a level comparable to control cells. MDA-MB-231 were pre-treated for 1 h with or without MG-132 (15 μM) or Bortezomib (25 nM) before treatment with carnosol at the indicated concentrations. Whole cells lysate were resolved on 8% SDS-PAGE and analyzed by Western blot for STAT3 and phospho-STAT3 protein.