A. Indicated breast cancer cell lines were transfected with 28nM scr or mimic for 72hrs in presence of doxorubicin (0.75μM) for 48hrs and cell proliferation was measured by MTT assay. Data are representative of three independent experiments. *, p < 0.05; **, p < 0.01; ***, p < 0.001. B. MDA-MB-231 and HCC1954 cells were transfected with scr or mimic for 72hrs in absence or presence of doxorubicin and autophagy marker LC3B-I and LC3B-II were monitored to examine autophagic flux. C. MDA-MB-231 cells were transfected with 9.3nM scr or mimic with or without siATG5 for 24hrs and treated with indicated concentration of doxorubicin for 48hrs and cell proliferation was measured by MTT assay. D. MDA-MB-231 cells were transfected with 9.3nM scr or mimic with for 24hrs and treated with indicated concentration of doxorubicin in presence or absence of Bafilomycin A1 (50nM) for 48hrs and cell proliferation was measured by MTT assay. Data are representative of three independent experiments. *, p < 0.05; **, p < 0.01; ***, p < 0.001.