TGFB1 and neoplasm: In osteoblastic lesions, as occurs in osteosarcomas and prostate cancer metastasis, tumor‐derived factors, including insulin‐like growth factor (IGF)‐1 and −2, TGF‐β, bone morphogenetic proteins (BMPs), platelet‐derived growth factor (PDGF), endothelin‐1 (ET‐1), and fibroblast growth factors (FGFs) stimulate the differentiation and bone‐forming activity of osteoblasts (reviewed in Guise and Mundy31).