The copper chaperone for SOD1 (hCCS) is highly specific for SOD1 and has a role in every stage of SOD1 maturation. Macrophage migration inhibitory factor (MIF) can reduce misfolded SOD1 accumulation on the surface of mitochondria. The heat shock protein (HSP) system is involved in both SOD1 folding, degradation and possibly breakdown of aggregates. This last step may provide seeds that propagate SOD1 misfolding and aggregation within the cell or in surrounding cells. HSP interactions with SOD1 are not specific but involve high-affinity binding to hydrophobic residues including SOD1 β-strand 7.