Breast cancer cells with a high expression of ErbB2 are more sensitive to glucose depletion than ErbB2-negative cells. (A) Overexpression of ErbB2 in MCF7 and MDA-MB-231 breast cancer cells, and siRNA knockdown of ErbB2 in BT474 breast cancer cells. Cells were transfected with vector containing wild-type ErbB2 or siErbB2. Whole cell lysates were subjected to western blot analysis, with β-actin used as a loading control. (B) 231V, 231ErbB2; MCF7, MCF7ErbB2 and BT474, BT474 siErbB2 cells were cultured in low glucose conditions for 48 h. ErbB2-overexpressing cells exhibited lower viability in low glucose conditions compared with control cells, which had significantly higher cell viability (top panels). The 231, MCF7 and BT474 cells were treated with 3-BrPA for 48 h at the indicated concentrations. Following this, cell viability was assayed (lower panels). (C) 231V and 231ErB2 cells were treated with 3-BrPA and cultured under low glucose condition for 48 h. The cell morphology and apoptosis were then examined by microscopy. Data are the mean values of three independent experiments; bars, SE. *P<0.05; **P<0.01; ***P<0.001.