Differentiation of Pax8-, NKx2-1–, or Pax8/NKx2-1–expressing mouse ES cell lines into thyroid cells. (A) qRT-PCR analysis for thyroid transcriptional factors (Pax8, NKx2-1, and Foxe1) in differentiated Pax8+, NKx2-1+, and Pax8+/NKx2-1+ ES cells at day 21. (B) qRT-PCR analysis for thyroid functional genes (NIS, TSHR, Tg, and TPO) in differentiated Pax8+, NKx2-1+, and Pax8+/NKx2-1+ ES cells at day 21. The relative expression of each transcript is presented as fold change compared to undifferentiated ES cells (mean±SEM) and represent one out of three separate experiments. All data were significant (p<0.01) when compared to control ES cells.