Neuroglobin (NGB) is a monomeric 17-kDa globin protein with a bis-histidyl six-coordinate heme-iron center that binds oxygen, carbon monoxide, and nitric oxide 12. While NGB's canonical role in oxygen transport remains uncertain due to its high oxygen affinity and low tissue abundance 13, it functions primarily as an endogenous neuroprotectant. Cerebral hypoxia and ischemia induce NGB expression, and neuronal overexpression reduces hypoxic-ischemic injury while knockdown exacerbates damage 4. NGB expression increases with aging, correlating with HIF-1α induction 5. Beyond oxygen binding, deoxygenated NGB exhibits nitrite reductase activity producing neuroprotective nitric oxide during hypoxia 6, and functions as a guanine nucleotide dissociation inhibitor toward G-alpha proteins, facilitating hypoxia-responsive neuroprotection 37. Recent evidence demonstrates NGB protects dopaminergic neurons in Parkinson's disease models by directly interacting with mitochondrial Complex I subunit NDUFA10, restoring its activity and inhibiting apoptosis 8. NGB overexpression also protects against Alzheimer's disease and mitochondrial dysfunction 9, though paradoxically facilitates cancer cell survival 9, positioning NGB as a critical cellular switch between death and survival pathways.