PGR and neoplasm: EMT is, for instance, most evident in “triple-negative” tumors [those without estrogen receptors (ER), progesterone receptors (PR), and human epidermal growth factor receptor 2 (HER2)] and HER2 positive (HER2+) tumors, and least frequent in ER positive (ER+) tumors, particularly lobular cancers, mirroring the metastatic potential of these tumor types (27, 30).