NOS2 and amyotrophic lateral sclerosis: An interplay among glial cells also takes place, since astrocytes expressing mutations characteristic of ALS increase microglial activation, upregulating the inducible nitric oxide synthase (iNOS), leading to further damage to motoneurons and accelerating disease progression through a non-cellular autonomous mechanism (Nagai et al., 2007; Yamanaka et al., 2008).