Stanniocalcin 1 (STC-1) is a homodimeric glycoprotein hormone that is involved in calcium and phosphate homeostasis. It was originally identified in bony fishes, where elevation of calcium in serum causes the release of STC from the endocrine glands called the corpuscles of Stannius. STC-1 inhibits the breakdown of PAPP-A, protects cancer cells from apoptosis, reduces tumor size of liver cancers, promotes osteoblast differentiation and inhibits longitudinal bone growth directly at the growth plate. It is also a biomarker of brain and lung cancer progression. STC1 signals through inhibitory G-protein modulates CGRP receptor spatial localization during osteoblastogenesis and may function as a regulatory factor interacting with calcitonin peptide members during bone formation.