TP53 and chronic obstructive pulmonary disease: As COPD pulmonary fibrosis injury is associated with damaged alveolar epithelia, research has mostly focused on damaged alveolar epithelia and found higher expression of p53 and PAI-1, as well as the activation of caspase-3, which participates in promoting apoptosis of alveolar epithelial cells (Bhandary et al., 2013).