MAPK8 and pulmonary fibrosis: The aims of this study were to observe the effects of thalidomide on a rat model of pulmonary fibrosis, to determine the protein expression levels of phosphorylated c-Jun N-terminal kinase (p-JNK) and α-smooth muscle actin (α-SMA) and to explore the mechanism underlying the preventive effect of thalidomide on pulmonary fibrosis.