SERPINE1 and idiopathic pulmonary fibrosis: Our results confirm that, compared to ATII cells in control lungs, ATII cells in IPF lungs express higher levels of PAI‐1 (Hogan et al., 2014) as well as p21 and p16 (Chang et al., 2010; Barkauskas & Noble, 2014), two‐cell senescence mediators.