Multiple senescence biomarkers accumulate in both fibroblasts and epithelial cells in IPF lungs including the expression of CDKN1A (p21), CDKN2A (p16), senescence-associated β-galactosidase activity (SA-βgal) and DNA damage (Kuwano et al. 1996; Schafer et al. 2017). Here, CDKN2A is linked to idiopathic pulmonary fibrosis.