P2RX7 and amyotrophic lateral sclerosis: Consistent with low basal levels of ATP release and trophic P2X7 action that have been observed in surveilling microglia (Monif et al., 2009), or massive ATP release increasingly occurring from injured motor neurons with consequent toxic roles exerted by P2X7 in activated microglia (Kettenmann et al., 2013; Monif et al., 2010), we demonstrated that antagonism of the receptor produces positive outcomes only at a certain stage and rate of progression of the disease, thus confirming and extending to ALS the dual role of P2X7.