TNF and amyotrophic lateral sclerosis: On the contrary, in vitro activation of P2X7 exacerbates proinflammatory responses, such as NADPH oxidase 2 (NOX2) activity, tumor necrosis factor-α (TNF-α), cyclooxigenase-2, and mitogen-activated protein kinase (MAPK) levels in ALS-microglia, and toxicity towards neuronal cells [21,22].