ABSTRACT
Transforming growth factor-β (TGF-β) is a multifunctional, secreted homodimeric protein that regulates tissue homeostasis by controlling a myriad of processes, such as cellular proliferation, differentiation, apoptosis, and migration. TGF-β1 is the prototypic member of a superfamily of more than 35 cytokines that includes the TGF-βs, the bone morphogenetic proteins (BMPs), growth and differentiation factors (GDFs), Nodal, and activins. The members of the TGF-β family play critical roles in embryonic development and adult tissue homeostasis, and any perturbations of the signaling pathways underlie developmental disorders and human disease (Massagué et al. 2000).
