In particular, we analyzed transgenic mice carrying TRK and RET/PTC3 oncogenes, which develop papillary thyroid carcinomas (PTC) [57, 58] and N-ras mice that develop thyroid follicular tumors that undergo dedifferentiation, predominantly follicular thyroid carcinoma (FTC) [59]. Here, RET is linked to thyroid cancer, nonmedullary, 2.