Over-expression of aspartate aminotransferase (AAT) in MDA-MB-231 breast adenocarcinoma cells confers resistance to oxamate and AAT-specific siRNA suppresses MDA-MB-231 cell proliferation. (a) MDA-MB-231 cells were stably transfected with AAT or empty vector and examined for AAT expression by Western blot analysis. (b) Densitometry of Western blot after over-expression of AAT. (c) Cells were incubated with the indicated concentrations of oxamate, and viable cells were counted after 48 hours. Control cells containing an empty vector were similarly examined. *p < 0.01 represents statistical difference between control and oxamate-treated samples. (d) MDA-MB-231 cells were untreated (control), sham-transfected with Oligofectamine alone (oligo) or transfected with AAT-specific siRNA molecules (AAT1-3) or lamin-specific control siRNA (Lamin) and examined for AAT expression by Western blot analysis. (e) Densitometry of Western blot after siRNA transfection. (f) Viable cells were counted 48 hours after siRNA transfection. Data are plotted as the mean ± standard deviation.