Marques and colleagues reported high levels of iron in macrophages, with TfR and FPN upregulation in breast cancer tissues, while Leftin et al. reported that the depletion of iron-laden TAMs, using small-molecule inhibitors of the macrophage colony stimulating factor 1 receptor (CSF1R) or anti-CSF1R IgG in a murine breast tumor model, slowed mammary tumor growth, leading to the conclusion that iron deposition in macrophages can contribute to their tumor-supportive role [97,98]. This evidence concerns the gene SLC40A1 and breast cancer.