SOD1 and amyotrophic lateral sclerosis: Most likely, the upregulated transforming growth factor-β1 (TGF-β1) in murine and human ALS astrocytes regulates the inflammatory response of microglia as demonstrated in a study of Endo, reporting that the astrocyte-specific overproduction of TGF-β1 in SOD1(G93A) mice accelerates disease progression via IGF-I production in deactivated microglia.