Opioid growth factor receptor (OGFR) is a receptor for [Met(5)]-enkephalin and plays important role in the regulation of cell growth and embryonic development. Opioid growth factor receptor (OGFr) facilitates growth inhibition in the presence of its specific ligand opioid growth factor (OGF), chemically termed [Met(5)]-enkephalin. The function of the OGF-OGFr axis requires the receptor to translocate to the nucleus. The opioid growth factor (OGF)-OGF receptors (OGFr) axis plays an important role in the homeostasis and re-epithelialization of the mammalian cornea. This tonically active growth regulatory inhibitory pathway is involved in cell replication, and the endogenous neuropeptide OGF targets cyclin-dependent kinase inhibitors, p16 and/or p21. The opioid growth factor receptor (OGFr) mediates the inhibitory action of OGF on cell replication of normal and neoplastic cells.