Fibroblasts were found to play a central role in the fibrotic process and contributed to histological features of IPF lung tissues because fibroblasts were accompanied by an increased intracellular ROS generation in IPF patients compared with the healthy controls, and ROS was an essential mediator of Smad2/3 transcription factor activation in response to TGF-β in fibroblasts28. The gene discussed is SMAD2; the disease is idiopathic pulmonary fibrosis.