Building on our previous results, showing that PATZ1 is downregulated in human thyroid carcinomas and plays a tumor suppressor role in thyroid cancer cells by inhibiting their malignant phenotype [10,22], we intercrossed RET/PTC1TG [13] with Patz1-knockout mice [21] to better define the role of PATZ1 in thyroid carcinogenesis driven by the RET/PTC1 oncogene. This evidence concerns the gene RET and thyroid cancer.