TGF-B1 (transforming growth factor-beta) is a multifunctional protein that controls proliferation，differentiation and other functions in many cell types. Many cells synthesize TGFB1 and have specific receptors for it. It positively and negatively regulates many other growth factors. It plays an important role in bone remodeling as it is a potent stimulator of osteoblastic bone formation，causing chemotaxis，proliferation and differentiation in committed osteoblasts. It also stimulates sustained production of collagen through the activation of CREB3L1 by regulated intramembrane proteolysis.
