TGFB1 and osteosarcoma: As a stimulator of proliferation, TGFβ induces expression of fibroblast growth factor 2 in human renal fibroblasts, and platelet-derived growth factor in glioma and osteosarcoma cells.24, 25, 26 In normal prostatic epithelial cells, TGFβ acts as a growth suppressor by inhibiting proliferation and inducing apoptosis, whereas in prostate cancer cells, which have lost sensitivity to TGFβ-induced growth arrest, TGFβ may promote tumor cell growth.