Parathyroid Hormone-Related protein (PTHRP) is a member of the parathyroid hormone family. PTHRP is known as a potent inhibitor of chondrocyte maturation. PTHRP is a critical regulator of cellular and organ growth, development, migration, differentiation and survival and of epithelial calcium ion transport. PTHRP also regulates epithelial-mesenchymal interactions during the formation of the mammary glands. During endochondral bone development, PTHRP plays a major role in suppressing the onset of hypertrophic differentiation. Defects in PTHRP are the cause of Brachydactyly Type E2.