Furthermore, the authors demonstrated a reduction of progesterone-induced proliferation when RANKL signaling was inhibited with denosumab (a monoclonal antibody to RANKL that is widely used to treat osteoporosis and to prevent skeletal events in breast cancer patients with metastases [25–27]) in a 3D-organoid model derived from mammary cells with a mutation in BRCA1 and breast biopsies from BRCA1 mutation carriers [23]. The gene discussed is BRCA1; the disease is osteoporosis.