[Transforming growth factor-betas: smad signaling and roles in physiopathology].

Transforming growth factor-beta (TGF-beta) family members are multifunctional peptide growth factors that regulate cell growth, differentiation, extracellular matrix production and cell migration and embryonic development. Knock-out experiments for the three mammalian isoforms of TGF-beta in mice have demonstrated their importance in regulating inflammation and tissue repair. Also, TGF-beta has been implicated in the pathogenesis of human diseases, including tissue fibrosis and carcinogenesis. In the latter case, it may exert both tumor suppressor and pro-oncogenic activities depending on the stage of the tumor. Smads proteins constitute the core components of the intracellular signaling cascade initiated by TGF-beta receptors, as they carry signals from the cell surface directly to the nucleus; where they act as transcription factors.