Genes related to cytoprotection and antioxidant response (e.g., Gsta3, Gstm1, Nqo1, Gpx2), as well as the H2O2-producing gene Aox1 that is usually decreased in thyroid cancers [31], were all downregulated in thyroids of KO mice (Figure 2D), as found previously in other tissues [32,33]. This evidence concerns the gene GPX2 and thyroid cancer.