H2AZ2 and chronic obstructive pulmonary disease: From among the putative target genes of the 5 miRNAs generalizing to severe COPD exacerbations, 20 nodes with high degree were considered hub proteins: UBA52, EGFR, MAPK1, JUN, ACTB, VEGFA, CDH1, HSPA8, MDM2, MTOR, SMARCA4, GSK3B, PIK3R1, FBXL19, EIF4E, H2AFV, HNRNPA1, CDK2, ATG7, and RELA (Supplemental Table S2).