CDKN2A and idiopathic pulmonary fibrosis: CDKN2A (p16, INK4A), a tumor suppressor gene, is one of the INK4 class of cell cycle inhibitors,[27] which is involved in the regulation of cell proliferation and apoptosis.[28] CDKN2A is not only one of the CRGs, but also a member of the ferroptosis- and cellular senescence-related genes.[7,29] Consistent with the results of previous studies,[30,31] CDKN2A expression level was upregulated in lung tissue of IPF patients.