Growth Hormone (GH or hGH) , also known as somatotropin or somatropin, is a member of a family of growth factors that includes prolactin, placental lactogens, proliferins, and somatolactin. GH is a peptidic hormone produced by somatotrophs of the anterior pituitary gland. The GH1 gene, along with 4 additional related genes, is located at the growth hormone locus on chromosome 17. The five genes share a remarkably high degree of sequence identity. Alternative splicing results in 5 isoforms ranging from approximately 19 kDa to 24 kDa. 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. Anti-Growth Hormone stains somatotrophs in normal pituitary tissues and is useful in identifying pituitary tumors, and understanding pituitary disease or acromegaly. Studies have also found Anti-GH to stain non-pituitary cells, such as hepatocellular carcinoma and cutaneous lesions.