In addition, abundant plasminogen activator inhibitor 1 (PAI-1) is found in both AT2 cells and fibroblasts of aged mice, PAI-1 can drive bleomycin (BLM) and doxorubicin-induced AT2 cell senescence and pulmonary fibrosis through activating p53/p21/Rb pathway-mediated cell cycle repression [100]. The gene discussed is SERPINE1; the disease is pulmonary fibrosis.