BRAF and thyroid cancer: To investigate the role of FOXE1 gene dosage in thyroid cancer development, we used the double transgenic Tg-rtTA/TetOBRAFV600E mouse model (BRAF) bearing the reverse tetracycline transactivator (rtTA) under the control of the thyroglobulin (Tg) promoter and the BRAFV600E oncogene under the control of a modified tetracycline operator (TetO).