TPO and thyroid gland undifferentiated (anaplastic) carcinoma: In this study, we attempted to induce differentiation of papillary and anaplastic thyroid carcinoma cells as measured by the induction of NIS, TPO, TG, and TSHR by exposing the cells to 5-Az, histone deacetylase inhibitors (suberoylanilide hydroxamic acid (SAHA) and valproic acid), ATRA, 9-cis RA, troglitazone (PPARγ ligand), 1,25-dihydroxyvitamin D3 (1,25(OH)2D3), thyroid hormone T3, and thyrotropin-stimulating hormone.