TGFB1 and osteosarcoma: On the other hand, activated osteoclasts secrete calcium ions, insulin like growth factors (IGFs) and transforming growth factor‐β (TGF‐β), which promote osteosarcoma cell proliferation and invasion.[5] Many current osteosarcoma treatment drugs, such as bisphosphonates, RANKL antibody, and tyrosine kinase inhibitors, target osteoclasts to disrupt the vicious cycle between tumor proliferation and osteoclastogenesis.[6] Nevertheless, merely osteoclast inhibition is usually insufficient to control the progression of osteosarcoma.