Metastasis suppressor protein. May regulate events downstream of cell-matrix adhesion, perhaps involving cytoskeletal reorganization. Generates a C-terminally amidated peptide, metastin which functions as the endogenous ligand of the G-protein coupled receptor GPR54. The receptor is essential for normal gonadotropin-released hormone physiology and for puberty. The hypothalamic KiSS1/GPR54 system is a pivotal factor in central regulation of the gonadotropic axis at puberty and in adulthood. In the hypothalamus, expression increases with puberty in both male and female monkeys. Robust expression in the region of the arcuate nucleus (ARC). Belongs to the KISS1 family.