Wnt signaling in osteoblasts regulates expression of the receptor activator of NFkappaB ligand, and inhibits osteoclastogenesis in vitro[47] (while Dickkopf1, a secreted Wnt/beta-catenin antagonist, produced by breast tumor cells is an important mechanistic link between primary breast tumors, and secondary osteolytic bone metastases [42]. The gene discussed is DKK1; the disease is breast neoplasm.