SLC40A1 and colonic neoplasm: Dmt1, Tfr1 and Fpn protein expression have been shown to be upregulated in mouse and human colorectal adenoma and/or carcinoma.[19], [58] Downregulation of Fpn expression, however, has been reported in other cancers and is associated with a poor prognosis in breast cancer.[59] Iron staining in the colonic tumors was not detectable (Fig. 7D) suggesting that the increased iron taken up by the tumors did not accumulate but was instead utilized for cell proliferation.