ID1 and pulmonary fibrosis: Genetic and pharmacological approaches were used <i>in vivo</i> to determine the role of ID1/ID3 in pulmonary fibrosis.<h4>Results</h4>ID1/ID3 levels were elevated in lungs and lung fibroblasts from mice and patients with pulmonary fibrosis, as well as in HLFs treated with TGF-β.