CD14 and amyotrophic lateral sclerosis: It was revealed that extracellular SOD1 is not directly involved in the pathogenesis of ALS; however, it utilizes CD14 (Cluster of differentiation 14)-TLR2 pathway, which is triggered through the activated microglia-mediated release of TNF-α [44] that subsequently aggravate motor neuron degeneration, a characteristic feature in ALS.