The expression of Pax-8 and TTF-1 is low in thyroid carcinoma (Ros et al, 1999); and stable transfection with a Pax-8 expression vector in anaplastic thyroid carcinoma cell line, ARO, caused re-expression of endogenous NIS, TG, and TPO (Presta et al, 2005). The gene discussed is TPO; the disease is thyroid gland undifferentiated (anaplastic) carcinoma.