PDI decreases SOD1 monomers as well as multimers. a Lysates from HEK293A cells transfected with SOD1 and PDI were examined by Western blotting under nonreducing conditions. b, c PDI decreased the relative level of mSOD1 (G93A) protein (shown on Y-axis), and the decrease was observed for both monomers (b) and multimers (c). However, the PDI-induced decrease in SOD1 levels was accentuated for SOD1 monomers of both the wild-type and mutant (SOD1: WT wild-type, G93A G93A mutant, Moc mock-transfected). Values are mean + SEM, n =4; *P <0.01, **P <0.001