Figure 3

GB235 in combination with Trastuzumab reversed resistance induced by heregulin-α in BT-474 cells by the restraining heregulin-α/HER3 pathway. (A) In the presence of exogenous heregulin-α, the BT-474 cells were resistant to Trastuzumab. With the addition of GB235 to Trastuzumab, BT-474 cells recovered sensitivity to Trastuzumab. The data are expressed as the mean ± SEM of three independent experiments. ***p < 0.001. (B) Serum-starved BT-474 cells pretreated with GB235 (20 µg/mL), Trastuzumab (20 µg/mL) alone or in combination, then stimulated by heregulin-α, and immunoblotted.