TPO and thyroid gland carcinoma: On one hand, Tg-BrafV600E;Tshr-/-mice [27] and LSL-BrafV600E;TPO-Cre;Tshr-/- mice [4], both of which are unresponsive to TSH stimulation due to a lack of TSH receptor expression, can develop thyroid cancers, albeit less aggressive, but, on the other hand, transplantation of thyroid cancers developed in LSL-BrafV600E;TPO-Cre mice (with high TSH levels) into nude or syngeneic immuno-competent mice (with normal TSH levels) leads to regression and senescence [28].