MAPK3 and pulmonary fibrosis: Controversially, Watanabe-Takano et al. have shown that the Ras-ERK1/2 pathway negatively regulates TGF-β1-induced EMT in pulmonary fibrosis, and DA-Raf1 plays a pivotal role in EMT, as a dominant agonist of the Ras-ERK1/2 pathway.