Osteolytic factors produced by osteosarcoma cells, such as interleukin-6 (IL-6), IL-11, receptor activator of NF-κB ligand (RANKL) and tumor necrosis factor-α lead to bone degradation and in consequence release of TGF-β into the tumor microenvironment [80]. Here, TGFB1 is linked to osteosarcoma.