TGF-β1, the most well characterized pro-fibrotic mediator in pulmonary fibrosis, is a cytokine secreted by a wide range of cell types including fibroblasts, with effects that are cell type and tissue specific (Coffey et al., 1988; Pietenpol et al., 1990; Bendelac et al., 1997; Thannickal et al., 2003; Kronenberg and Rudensky, 2005; Leveen et al., 2005; Marie et al., 2006; Li et al., 2007; Liu et al., 2008). Here, TGFB1 is linked to pulmonary fibrosis.