TSHR and thyroid gland follicular carcinoma: Moreover, by using a TSHR-knockout mouse model (TSHR(-/-)) to study the role of TSH/TSHR-mediated growth signaling, it was discovered that existing additional oncogenic mutation, such as that in TRbeta(PV/PV) mice, is indispensable for follicular thyroid cancer (FTC) cells to metastasize [101], indicating that although the signaling transduction downstream of TSH/TSHR plays an important role in modulating thyroidal cell proliferation, other coexisting mutations capable of turning on other signaling cascades are required to establish an invasive phenotype.