It is also worth studying whether there exists a smoking-induced deubiquitinase activation in the body that could promote the senescence of EPCs to participate in the process of COPD through stabilizing the expression of p300 protein, upregulating the acetylation level of histone H4K12, and activating the transcription of senescence-related factors. The gene discussed is EP300; the disease is chronic obstructive pulmonary disease.