The OPG-RANKL-RANK axis mediates a vicious cycle central to this process: Tumor-secreted IL-6 and parathyroid hormone-related peptide stimulate osteoblasts to produce RANKL, which binds to RANK on osteoclasts, initiating bone resorption and releasing growth factors such as TGF-β that support tumor growth (9). The gene discussed is TGFB1; the disease is neoplasm.