Fig. 1.

Iodide suppression of NIS expression at the mRNA and protein levels in FRTL-5 thyroid cells. FRTL-5 cells were treated with either sodium chloride (NaCl) or sodium iodide (NaI) for 48 h. The final concentrations added to the cells were 0, 0.1, 1, 2.5, 5, 7.5, and 10 mM. NIS and β-actin were detected by Northern hybridization. (B) FRTL-5 cells were treated with 10 mM NaI for 6 or 48 h. NIS protein level was measured by Western blotting. Actin was used as a control.