There was no significant difference in the level of bFGF, HGF, transforming growth factor beta-1 (TGF-β1), and platelet-derived growth factor-AA (PDGF-AA) in conditioned medium (CM) from either NHLF or IPF fibroblast mono-cultures (Additional file 2). This evidence concerns the gene HGF and idiopathic pulmonary fibrosis.