SOD1 and amyotrophic lateral sclerosis: EVs secreted from active astrocytes in the brain of patients with Parkinson's disease (PD) enhance the degeneration of dopaminergic neurons by enrichment of miR-34a 11 and aggravate motor neuron degeneration in the amyotrophic lateral sclerosis (ALS) model via transfer of depleted miR-494-3p 12, toxic SOD1, TDP-43, and FUS 6.