Tb-12, or Transforming growth factor beta regulator 4, is a human gene encoded by TBRG4. It may also be known as: Protein TBRG4; Cell cycle progression protein 2; FAST kinase domain-containing protein 4; Cell cycle progression restoration protein 2; FAST kinase domains 4; cell cycle progression 2 protein; CPR2; FASTKD4. The encoded protein has an amino acid length of 631 and a mass of 70.7 kDa. Tb-12 is a member of the FAST kinase family. Homologs of this gene exist in other organisms, including: Mouse, Rat, Zebrafish, Frog, Chicken.