For example, Shen, W. et al. detected the mRNA expression levels of MBD2, miR-301a-5p, CXCL12 and CXCR4 in PBMCs from healthy controls and patients with stable COPD or with an acute exacerbation of COPD, and found that the MBD2/miR-301a-5p/CXCL12/CXCR4 pathway was shown to affect the migration of lung fibroblasts and monocyte-derived macrophages, which may play an important role during COPD exacerbations (Shen et al., 2020). The gene discussed is MBD2; the disease is chronic obstructive pulmonary disease.