PPARG and thyroid gland carcinoma: Treatment of RAI-refractory thyroid cancer patients with retinoic acid [212], epigenetic transcriptional restoration of NIS expression via histone deacetylase inhibitors (HDACi) [213], or peroxisome proliferator-activated receptor (PPAR)-γ agonist [214] have shown sub-optimal re-differentiation outcomes for the patients.