Growth hormone-releasing hormone (GHRH) stimulates secretion and synthesis of growth hormone (GH), causes somatotroph proliferation and may have direct actions in fetal/placental development, reproduction and immune function. It exerts its action through high-affinity GHRH receptors present in the anterior pituitary. GSH-1 (GS homeobox 1) is a 264 amino acid hypothalamic nuclear protein that functions as a transcription factor responsible for maintaining GHRH expression as well as playing an important role in pituitary development. Coexpression of CBP leads to significantly enhanced GSH-1-induced GHRH expression, which suggest that CBP may function as a co-activator. Knockdown of GSH-1 mRNA in mice causes a dwarf phenotype, which suggests that certain cases of familial dwarfism may be caused by a mutation of the GSH-1 gene.