In fact, GSDMB upregulation is functionally involved in mediating HER2 BC’s aggressive behavior in multiple ways, since it enhances cancer cell migration and invasion, in vivo tumorigenesis (in GEMMs and orthotopic xenografts [44,190]), metastasis [44,45], and resistance (innate and acquired) to anti-HER2 therapies [43,188]. This evidence concerns the gene GSDMB and breast cancer.