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. Author manuscript; available in PMC: 2012 Oct 4.
Published in final edited form as: Horm Metab Res. 2009 Apr 8;41(6):488–499. doi: 10.1055/s-0029-1215572

Fig. 1.

Fig. 1

Schematic representation of PKA and PI3K signaling pathways in normal thyroid follicular cells under the control of TSH. TSH is the major growth regulator of thyroid follicular cells. Binding of TSH to TSHR activates the PKA, PI3K and other signaling pathways, leading to proliferation and differentiation of follicular cells. The differentiated follicular cells produce thyroid specific proteins such as thyroglobulin (TG), thyroid peroxidase (TPO), thyroid-stimulating hormone receptor (TSHR), and sodium/iodide symporter (NIS) to direct synthesis and release of thyroid hormones, T3 and T4. I-TG: iodinated-TG.