TBRG4 (transforming growth factor beta regulator 4), also known as CPR2 (cell cycle progression restoration protein 2) or FAST 4 (FAST kinase domain-containing protein 4), is a 631 amino acid protein that contains one RAP domain and belongs to the FAST kinase family. TBRG4 is ubiquitously expressed and may have a role in cell cycle progression. Existing as two alternatively spliced isoforms, the gene encoding TBRG4 maps to human chromosome 7p13. Chromosome 7 is approximately 158 million bases long, encodes over 1000 genes and makes up about 5% of the human genome. Chromosome 7 has been linked to Osteogenesis imperfecta, Pendred syndrome, Lissencephaly, Citrullinemia and Shwachman-Diamond syndrome.