STAT3 and idiopathic pulmonary fibrosis: In addition to STAT1, putative STAT3 binding sites were identified within the promoter region of SOCS1. Neither the level of methylation of the SOCS1 promoter at these putative STAT transcription factor binding sites or across the SOCS1 gene was different between IPF and HLF fibroblasts, and IPF and non-IPF lung tissue, suggesting that this is not the mechanism of regulation of SOCS1 expression in IPF lung tissue generally and fibroblasts in particular.