For fibroblasts, mitophagy is reduced during pulmonary fibrosis, leading to insufficient ROS clearance, the differentiation of myofibroblasts and the formation of fibroblast foci.240,241 For type II alveolar epithelial cells, as IPF lungs age, the expression of PINK1 decreases, which causes mitochondrial swelling and defects in mitophagy, promoting changes in lung fibers.242,243 It is worth mentioning that these three types of lung cells influence each other in the progression of fibrosis. The gene discussed is PINK1; the disease is pulmonary fibrosis.