Transforming growth factor beta-1 (TGF-beta 1) is a multifunctional protein that controls proliferation, differentiation and other functions in many cell types. The inactive form consists of a TGF-beta 1 homodimer non-covalently linked to a latency-associated peptide (LAP) homodimer. The active form is a homodimer of mature, disulfide-linked TGF-beta 1. 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. Defects in TGF-beta 1 are the cause of Camurati-Engelmann disease (CE), also known as progressive diaphyseal dysplasia 1 (DPD1). CE is an autosomal dominant disorder characterized by hyperostosis and sclerosis of the diaphyses of long bones. The disease typically presents in early childhood with pain, muscular weakness and waddling gait, and in some cases other features such as exophthalmos, facial paralysis, hearing difficulties and loss of vision.