TNFSF11 and breast cancer: Although BCCs cannot directly resorb bone, bone metastases in the setting of breast cancer are frequently osteolytic.8,9 Osteoclastogenesis is paradoxically facilitated by osteoblasts through the production of receptor activator of NF-κB ligand (RANKL) and osteoclastogenic cytokines.10 Skeletal remodeling is tightly regulated through the actions of osteoclasts and osteoblasts.