Metastatic breast cancer triggers disruption of bone homeostasis, and ultimately results in formation of osteolytic bone lesions 1, 9.During osteoclastogenesis induced by cancer cells, RANK/RANKL signaling has been confirmed to stimulatethe expression of key transcription factors including: nuclear factor κB (NFκB), activator protein-1 (AP-1), and nuclear factor of activated T-cells cytoplasmic 1(NFATc1)7, 45. The gene discussed is TNFSF11; the disease is cancer.