NDUFV2 and major depressive disorder: mRNA and protein levels of three subunits of complex I, NDUFV1, NDUFV2 and NDUFS1, all forming one functional subunit, were assessed in postmortem brain specimens of striatum and cerebellum of patients with schizophrenia, bipolar disorder or major depression and normal subjects, and analyzed together with our previous data from prefrontal and parieto-occipital cortices of the same cohorts.