The activation of the mesenchymal–epithelial transition (MET) factor receptor tyrosine kinase signaling pathway may be more related to resistance to HER2-targeted tyrosine kinase inhibitors (TKIs) in basal-like HER2+ BC cells, while HER2-HER3 heterodimerization is more linked to drug resistance in luminal-like HER2+ BC cells [162]. The gene discussed is ERBB2; the disease is breast cancer.