Lately, a study found a strong decrease in DAAO levels in idiopathic pulmonary fibrosis and bleomycin‐induced mouse fibrotic lung tissues [141]: d‐Ser treatment, as well as DAAO inhibition, promoted cellular senescence through the p53/p21 pathway, and the anti‐fibrotic effect of triiodothyronine depended on the DAAO levels. This evidence concerns the gene DAO and pulmonary fibrosis.