CASR is a calcium-sensing receptor and plays an important role in regulating PTH secretion. It is expressed in many different tissues, such as parathyroid, pancreatic islet and insulinoma cells, breast, gastrinoma cells, pituitary, keratinocytes and human colon epithelial cells. CASR Inhibits PTH secretion and parathyroid cellular proliferation in parathyroid glands or cells, and also inhibits proliferation of colonic crypt cells. Besides, it can stimulate PTHrP secretion in prostate cell line, and stimulate calcitonin secretion from thyroidal C-cells.