NTRK1 and medullary thyroid gland carcinoma: Some of the key cancer genes up-regulated in T1/FTC included thyroid gland-specific genes like TRHR, TSHR, PAX8, and fibroblast growth factor receptors, FGFR2 and FGFR. Genes up-regulated in T2/MTC group included RET, NTRK1, and MYC (Fig. 3B).