NIS expression in different tissues. A: Radioiodide accumulation in NIS-expressing human tissues (SG: salivary glands, T: thyroid, G: stomach) 2 hours after 99mTc-pertechnetate administration (5 mCi). B: Immunoblot analyses of human NIS expression in a Graves' thyroid (T), normal salivary glands (SG), and normal gastric mucosa (G). Total protein (50 μg) was electrophoresed into each lane; the nitrocellulose membrane was probed with 3 nM affinity-purified anti-human-NIS Ab as described in Materials and Methods. C-H: Immunohistochemical analyses of NIS expression in human iodide-concentrating tissues. C: Normal thyroid (original magnification: 400 ×), D: Graves' thyroid, strong basolateral NIS staining of the follicular epithelial cells (original magnification: 1,000 ×), E: Salivary gland (original magnification: 400 ×), F: Basolateral NIS staining in the salivary ductal cells (original magnification: 1,000 ×), G: Gastric mucosa (original magnification: 400 ×), H: Basolateral NIS staining of the gastric mucin-secreting cells (original magnification: 1,000 ×).