EGFR and chronic obstructive pulmonary disease: The functional enrichment analysis reported that the three miRNAs regulate different pathways that are involved in COPD processes, such as adherents junction, ErbB signaling pathway, Notch signaling pathway, and Wnt signaling pathway (miR-449c-5p); PI3K-Akt signaling pathway, p53 signaling pathway, tight junction, Hippo signaling pathway, ErbB signaling pathway, ubiquitin mediated proteolysis, TGF-beta signaling pathway, and Wnt signaling pathway (miR-200c-3p); and Hippo signaling pathway, cellular senescence, and mTOR signaling pathway (miR-320c) (Figure 4).