Schematic representation of Ad.sTβRFc-mediated inhibition of bone metastases and osteolytic bone destruction. See text for details. IGF-1, insulin-like growth factor-1; IL-11, interleukin-11; PTHrP, parathyroid hormone-related protein; RANKL, receptor activator of nuclear factor-κB ligand; sTGFβRIIFc, soluble form of transforming growth factor-β receptor II fused with human immunoglobulin Fc fragment; TGF-β, transforming growth factor-β; TRAP, tartrate-resistant acid phosphatase.