Fig 1: Lower expression of JUN and FOS and positive correlation to RXFP1 in control and IPF lungs and lung fibroblasts.Lung tissue expression levels of FOS analyzed using microarray (A) and JUN analyzed using bulk RNA sequencing (C) from the publicly available Lung Genomics Research Consortium (LGRC) gene expression dataset (GEO accession GSE47460; http://www.lung-genomics.org/) were compared between control (108 subjects for FOS and 22 subjects for JUN) and idiopathic pulmonary fibrosis (IPF) (160 subjects for FOS and 22 subjects for JUN). The mean and standard deviation for each group and Mann-Whitney U test p-values are shown. Correlation of FOS (B) and JUN (D) gene expression levels with RXFP1 was analyzed in IPF lungs (160 subjects for FOS and 22 subjects for JUN) using linear regression and the R2 and p-value are shown. (E) Protein levels of JUN and FOS in independent IPF and control lung fibroblast lines analyzed by western blot with antibodies specific for JUN (rabbit mAb, Cell signaling technology #9165) and FOS (mouse mAb, Protein tech # 66590-1-IG). GAPDH (rabbit mAb Abcam Abcam ab181602) was used as a sample loading control. Total proteins isolated from confluent fibroblasts using radioimmunoprecipitation assay (RIPA) were separated by SDS-PAGE gel electrophoresis. (F) Densitometry of the results on (E) using the ImageJ software (National Institutes of Health) [29]. For FOS, total density of both bands was used for each sample. A total of 10 independent lung fibroblast lines (5 IPF and 5 control) were analyzed.