Kogai et al. reported that RA stimulation of the NIS in MCF-7 breast cancer cells was meditated by the insulin growth factor-I/phosphatidylinositol 3-kinase and p38 MAPK signaling pathways and an inhibitor of p38 MAPK could significantly reduce iodide uptake in both all-trans retinoic acid-stimulated MCF-7 cells and TSH-stimulated FRTL-5 cells [33]. Here, SLC5A5 is linked to breast cancer.