Effects of combined treatment with SBHA and proteasome inhibitors on breast cancer cell apoptosis. MCF-7 cells were exposed to SBHA (40 μM), Bortezomib (5 nM), and MG-132 (250 nM), alone or in combination, for 72 h and cell apoptosis was examined. (A) Detection of DNA fragments via the DNA ladder assay. Representative image of DNA fragmentation are shown. (B) MCF-7 and (C) MDA-MB-231 cells were treated with SBHA, Bortezomib, and MG-132 alone or in combination, and cell apoptosis was assessed by annexin V staining assay. Results are expressed as mean ± SD of three independent experiments. Lane 1: molecular-weight marker; lanes 2-6: control, SBHA, Bortezomib, SBHA + Bortezomib, MG-132, and SBHA + MG-132 group, respectively. *P <0.05 vs. control; #P <0.05 vs. each reagent alone.