SOD1 and amyotrophic lateral sclerosis: Importantly, TDP-43, SOD1, and FUS are capable of forming amyloid fibrils in vitro (Chattopadhyay et al., 2008; Chen et al., 2010; Nomura et al., 2014), and there is also strong evidence to suggest that, for at least SOD1 and TDP-43, they adopt an amyloid formation in vivo (Kato et al., 2000; Bigio et al., 2013; Robinson et al., 2013), although there is not yet a consensus as classical amyloid stains are often negative in ALS cases (Neumann et al., 2006; Kerman et al., 2010).