Assistant Professor of Surgery & Research Health Scientist,

Faithful control of systemic Ca2+ homeostasis is cru-cial for life for most, if not all, multi-cellular organisms. In humans and many other vertebrates, extracellular Ca2+ is detected by a specific G-protein coupled receptor (GPCR) for divalent cations, the extracellu-lar Ca2+-sensing receptor (CaR) [1]. With this issue, I am pleased to launch a new review series in the Journal of Cellular and Molecular Medicine on this fascinating receptor. The idea that a sensor for extracellular divalent cations existed in mammals was not entirely new. It was apparent from early studies throughout the 1980s that some type of cell-surface receptor cou-pled to intracellular signal transduction cascades must be present on the parathyroid gland in order t