Mortalin is a mitochondrial chaperone and a member of the heat shock protein 70 family that is constitutively expressed in cells. Mortalin plays a central role in mitochondrial biogenesis through its capacity to direct the import of nuclear-encoded proteins into the mitochondria. Mortalin plays a role in the control of cell proliferation and elevated levels of mortalin have correlated with malignant transformation and poor cancer prognosis. Mortalin can support cancer cell resistance to complement-dependent cytotoxicity. Mortalin expression was decreased in the mitochondrial fraction of neurons from the substantia nigra of Parkinson disease patients.