Endogenous MIF accumulates at very low levels in the spinal neurons of mutant SOD1G85R mice. Shown are representative micrographs of lumbar spinal cord sections from SOD1G85R mice at the presymptomatic stage of the disease, processed for immunofluorescence using antibodies to MIF (A and D), antibodies to NeuN (for the identification of neurons) (B and E), and the merge of both, including DAPI staining (C and F). (Scale bars: A–C, 100 μm; D–F, 20 μm.)