Surprisingly, a significant proportion of Cu/Zn SOD1, known to be mainly localized in the cytosol31, was present as a stable 32-kDa dimer in the soluble fraction of extracts of MDA MB 468 breast cancer cells, as well as in DU145 prostate cancer cells treated with NSC 228155, but not with EGF, for 5 min or 10 min (Fig. S2a). Here, EGF is linked to breast cancer.