SH3BGRL and breast cancer: To address the potential pathological consequence and the impact of the interaction between SH3BGRL and HER2 on HER2-mediated signaling in breast cancer, we established SH3BGRL-overexpressing MCF-7 cells and SH3BGRL-depleted MDA-MB-453 cells (Fig. S1) and performed immunofluorescence staining to investigate the HER2 localization status in MDA-MB-453 cells.