While FGF-9 has been shown to be expressed in fibrotic human lung and human fibroblasts in response to TGF-β1 (Coffey et al., 2013) the studies presented here provide a putative mechanistic role for this molecule in pulmonary fibrosis via the accumulation of fibrocytes within the TGF-β1 exposed lung. This evidence concerns the gene TGFB1 and pulmonary fibrosis.