TGFB1 and pulmonary fibrosis: The results of the present study supported the previous studies of which PQ might induce pulmonary fibrosis, e.g., up-regulation of neurotransmitter, collagen synthesis and oxidative stress and down-regulation of epithelial cell differentiation, lung development and TGF-β signaling, cellular reactive oxygen species (ROS) in the PQ-treated rat lungs [4,6,8,9,11,41].