LIF and idiopathic pulmonary fibrosis: At first, we focused on the behavior of the WI-38 cells and LF-IPF from four different patients in response to the vehicle, TGF-β1 and Metformin treatment for 96 h, which induce the fibroblast (FIB), myofibroblast (MYF) and lipofibroblast (LIF) phenotypes, respectively (Figure 1A-B).