Although the noteworthy alteration in SOD levels has been described in malignant cells,47 its involvement in tumor progression and chemo‐resistance is still controversial.48, 49, 50, 51, 52 Results demonstrated that the mRNA expression levels of SOD2 and its enzymatic activity (Figure 4) were increased in the iron‐loaded cells when exposed to MTX. This evidence concerns the gene SOD1 and neoplasm.