KiSS-1 metastasis-suppressor (KISS1) is a metastasis suppressor gene that suppresses metastases of melanomas and breast carcinomas without affecting tumorigenicity. The metastasis suppressor properties may be mediated in part by cell cycle arrest and induction of apoptosis in malignant cells. Expression of KiSS1 has been localized to specific regions of the hypothalamus in many species and is regulated by gonadal steroids and across the estrous cycle.