SOCS1 and idiopathic pulmonary fibrosis: In this study, we used primary fibroblast cultures from normal and IPF lungs to investigate several mechanisms that are likely to contribute to reduced SOCS1 expression in IPF fibroblasts, including the kinetics of SOCS1 induction, SOCS1 promoter methylation, and the role of microRNA (miR)-155 as a negative regulator of SOCS1. We confirmed that SOCS1 mRNA levels are reduced in fibroblasts established from IPF patients compared to control fibroblasts, but this was not due to changes in the kinetics of induction of SOCS1 mRNA, altered SOCS1 promoter methylation, or regulation by miR-155.