Figure 2.

Addition of pertuzumab or patritumab to trastuzumab does not restore sensitivity in heregulin‐expressing cells. A and B, SKBR3‐HRG and BT474‐HRG cells were incubated for 120 h with increasing concentrations of trastuzumab and a fixed dose of pertuzumab (100 μg/mL) (A) or patritumab (100 μg/mL) (B); cell viability was then assessed with Cell Counting Kit‐8. Each point represents the mean ± standard error of 6‐wells from three independent experiments. C, SKBR3‐HRG and BT474‐HRG cells were incubated for 24 h in RPMI containing 2% FBS, after which cells were treated with or without trastuzumab (20 μg/mL), pertuzumab (20 μg/mL), and patritumab (20 μg/mL) for 1 h. Then, cells were lysed and subjected to immunoblot analysis for pAkt, Akt, pErk, and Erk, with β‐actin serving as a loading control