Consistent with previous reports,2,30 the cellular senescence markers p16 (CDKN2A) and p21 (CDKN1A) were significantly elevated in distal airway epithelium from IPF patients compared with controls, which were obtained from non-lesional lung segments of patients undergoing lobectomy for pulmonary nodules. Here, CDKN1A is linked to idiopathic pulmonary fibrosis.