LEF1 and idiopathic pulmonary fibrosis: When we examined the activity of LEF1 regulon in lung immune cells from upper lung lobes (IPF_ULL), which typically show very little histological change, and lower lung lobes (IPF_LLL), which are greatly affected by the disease (Jia, Rosas, et al., 2023; Morse et al., 2019), we found that overall, the activity was decreased in the upper lobe of IPF lungs, supporting the presence of aging/senescent cells.