TGFB1 and idiopathic pulmonary fibrosis: Initially, we demonstrated the ability of TGFβ1 to deliver a potent fibrotic stimulus in vitro using two typical endpoints with different human primary cell types from two organs: renal proximal tubular epithelial cells (RPTEC) and fibroblasts originating from idiopathic pulmonary fibrosis lung (IPF134).