Fig 1.

Cell-surface binding of HER3-DXd in MDA-MB-231 cells transduced with HER3^WT, HER3 mutations, or HER3^EV in the absence (A) or presence (B) of HER2 overexpression. Cells were incubated with 0.1, 1, 10, and 100 nM HER3-DXd, followed by secondary antibody (10 mg/mL Alexa Fluor 647 goat antihuman IgG). The cell-surface binding of HER3-DXd was assessed by flow cytometry and expressed as the mean fluorescence intensity of the cells that were stained positive for HER3-DXd. Abbreviations: EV = empty vector, HER = human epidermal growth factor receptor, WT = wild type.