TNFSF11 and neoplasm: Building on these foundations about the roles of the RANKL/RANK pathway in the immune system, bone metastasis, and many other physiological processes such as the proliferation and division of mammary epithelial cells as well as the mammary gland formation during lactation (Table 2) (37, 172–179, 182, 183), researchers have exploited the inhibitors targeting this axis to control the primary tumor development, reduce bone metastasis, and even exert a direct antitumor effect via regulating antitumor immune responses (180, 181).