Growth hormone (GH or hGH), also known as somatotropin or somatropin, is a peptide hormone that is produced and secreted by somatotrophs of the anterior pituitary gland. GH exerts a wide variety of biological actions in many different tissues and cell types. The actions of GH at the cellular level can be divided into three categories: those affecting mitogenesis, differentiation, and metabolism. The GH antibody specifically labels somatotrophs in pituitary in normal tissues. It is useful in classification of pituitary tumor.