C4B and amyotrophic lateral sclerosis: Rat primary cortical neurons were transfected with plasmids encoding wild-type (WT) (SOD1Ch) or ALS mutant SOD1 (G85RSOD1Ch, G93ASOD1Ch) alleles expressed as fusion proteins with a C-terminal monomeric Cherry fluorescent protein (Ch) tag; as a control, a plasmid encoding non-toxic protein Ch was transfected.