EPRS1 and pulmonary fibrosis: To investigate the physiological roles of EPRS in pulmonary fibrosis in vivo, WT (Eprs+/+) and Eprs−/+ hetero-knockout (KO) mice were treated with bleomycin to induce lung fibrosis by intratracheal instillation before analysis, since homozygous Eprs−/− is embryonic lethal.