These findings support the idea that secondary tumors in bone require an osteolytic environment, consistent with the “vicious cycle” model of bone metastases, in which tumor cells drive bone resorption to release osteolysis-derived factors (such as TGF-β, Calcium, or IGF-1) that enhance tumor cell survival [9, 84]. The gene discussed is TGFB1; the disease is neoplasm.