NRG1 and breast carcinoma: Neuregulin-1, a Schwann cell growth factor secreted by nerve cells,95 binds to its receptors—EGFR and HER2—on Schwann cells to mediate cell growth and migration; notably, overexpression of either neuregulin-196 or EGFR27 is sufficient to drive neurofibroma and MPNST tumorigenesis in mice.27 Therefore, a potential therapeutic strategy might be to target this neuregulin-1–EGFR axis,97 perhaps by repurposing the breast cancer drug trastuzumab.