The conditioned medium from bone metastatic MDA-BoM-1833, that expressed the highest levels of ZEB1 and of the BMP-inhibitors, led to the strongest osteoclast formation, compared to the parental MDA-MB-231, the lung metastatic MDA-LM2–4175 and the luminal breast cancer cell lines T47D and MCF7 (Fig. 5A). The gene discussed is ZEB1; the disease is breast cancer.