A similar effect on cell proliferation was recently observed in mesothelioma cell lines (33), hepatocellular carcinoma cells (34), and pancreatic cancer cells (16), although there was no effect on SMAD expression or phosphorylation but rather on p-ERK 1/2 (33) in mesothelioma cells or p-Stat3 in fibroblasts of IPF patients (35). Here, STAT3 is linked to idiopathic pulmonary fibrosis.