Transforming Growth Factor-beta 1 (TGF- beta 1) is a member of the TGF-beta superfamily. Members of this family are known to exhibit regulatory activity in immunity and prolife ion pathways. TGF- beta 1 signals through SMAD Proteins via the TGF- beta 1 RI and RII receptors. Mature TGF- beta 1 is a glycosylated homodimer, containing two 112 amino acids chains, with a total molecular weight of 25 kDa.