Parathyroid hormone-related protein (PTHrP) is a family of protein hormones produced by most if not all tissues in the body. It is secreted from a large and diverse set of cells, and during both fetal and postnatal life. Among tissues known to secrete this hormone are several types of epithelium, mesenchyme, vascular smooth muscle and central nervous system.^1,2 PTHrP is secreted from smooth muscle in many organs, usually in response to stretching. It acts to relax smooth muscle, thereby serving, among other things, as a vasodilating hormone. PTHrP may also have effects on contraction of muscle in the bladder, uterus and heart^1,2 and can play crucial roles in the cardiovascular system.³ PTHrP regulates proliferation and differentiation within the postnatal, cranial growth plate.⁴ PTHrP has been shown to have anabolic effects in women with postmenopausal osteoporosis. PTHrP promotes the recruitment of osteogenic cells and prevents apoptotic death of osteoblasts and osteocytes.⁵ PTHrP is a causative factor of humoral hypercalcemia of malignancy (HHM). It also causes cachexia including reduced food intake, body weight loss, and decreased locomotor activity by a mechanism that is independent of hypercalcemia and proinflammatory cytokine actions.⁶

AVSEHQLLHD KGKSIQDLRR RFFLHHLIAE IHTAEIRATS EVSPNSKPSP NTKNHPVRFG SDDEGRYLTQ ETNKVETYKE QPLKTP