C/EBP ? regulates gene expression in a variety of tissues including liver, adipose, lung and intestine. C/EBP ? is a basic region/leucine zipper transcription factor selectively expressed during the differentiation of liver, adipose tissue, blood cells and the endocrine pancreas. C/EBP ? uses a bipartite structural motif to bind DNA and appears to function exclusively in terminally differentiated, growtharrested cells. In the liver, C/EBP ? is a transactivator of several genes, which are regulated by growth hormone. Growth hormone enhances not only the levels of C/EBP ? mRNA and protein, but also the DNA-binding activity of C/EBP ?. C/EBP ? functions as an important transcription factor that regulates different genes, including Prolactin gene expression.