ACO1 and amyotrophic lateral sclerosis: On the other hand, the effect of increased SOD1 activity on IRP1 protein level has been investigated in cells overexpressing wild-type SOD1 gene as well as in transgenic SOD1G93A and SOD1G37R ALS cellular (Danzeisen et al., 2006) and mouse (Massignan et al., 2007; Jeong et al., 2009) models, but discrepant data on IRP1 regulation have been reported.