SOD1 and amyotrophic lateral sclerosis: Diminished expression of mutant SOD1 in astrocytes delays microglial activation and significantly reduces disease progression in ALS mice [38], [39], a fact suggesting that noxious signals from astrocytes do contribute significantly to the progression of non-cell autonomous killing of motor neurons in ALS via activation of both microglia and astrocytes, although ablation of proliferating microglia or astrocytes does not affect motor neuron degeneration in SOD1-ALS [31], [40].