Recently, the increased expression of Dio2 and decreased expression of Ppargc1a (peroxisome proliferator-activated receptor gamma coactivator 1-alpha), a master regulator of mitochondrial biogenesis, had been shown in a mouse model of refractory lung disease, idiopathic pulmonary fibrosis (IPF) [20]. Here, DIO2 is linked to idiopathic pulmonary fibrosis.