While not relevant in E2-supplemented murine models that lack aromatase in bone [63,64], TGFβ-stimulated aromatase expression in human osteoblasts [65] could support local increases in E2 surrounding osteolytic ER+ BMETs, thus, further contributing to a vicious cycle tumor-driven osteolysis even in post-menopausal patients. The gene discussed is TGFB1; the disease is neoplasm.