The novelty of this study lied upon the inhibitory mechanism elucidation, since they demonstrated that treatment with CORM-2 up to 100 μM and for 24 h (Figure 2(B)), as a source of CO, increased wild type (WT) p53 expression in MCF-7 breast cancer cells, while it reduced mutant p53 levels in MDA-MB-231 breast cancer cells. This evidence concerns the gene TP53 and breast cancer.