We exploited the Hb9-MitoEGFP mouse to visualize mitochondrial distribution and morphology in the context of mutant SOD1-mediated ALS in previously characterized transgenic mouse lines expressing either of two ALS-linked SOD1 mutants, SOD1G37R (dismutase active) and SOD1G85R (dismutase inactive). The gene discussed is MNX1; the disease is amyotrophic lateral sclerosis.