NQO1 and lactic acidosis: A pathway for electron transfer from NADH to mitochondria has recently been identified with the demonstration that idebenone is a good substrate of cytosolic dicoumarol-sensitive NQO1 [35]; and that rescue of ATP levels by idebenone in different cell types correlated with expression of NQO1, which may provide an effective electron transfer from cytosolic NAD(P)H to idebenone and then complex III, thus reducing lactic acidosis in patients with complex I deficiency [35].