Immunohistochemical analysis of TRK-T1 transgenic mouse thyroids revealed TRK-T1 staining within the thyroid follicular epithelium.     ///    These data support the conclusion that TRK-T1 is oncogenic in vivo and contributes to the neoplastic transformation of the thyroid..     ///    "To determine if TRK-T1 expression can cause thyroid cancer in vivo, we developed transgenic mice that express the human TRK-T1 fusion protein in the thyroid. "    ///    The TRK-T1 fusion protein induces neoplastic transformation of thyroid epithelium.. 