CCN2 and chronic obstructive pulmonary disease: Abbreviations: connective tissue growth factor—CTGF, alpha-smooth muscle actin—α-SMA, aspartate transaminase—AST, alanine aminotransferase—ALT, interferon gamma—IFNγ, chemokine (C-X-C motif) ligand-8—CXCL8, C-C motif ligand-2—CCL2, chronic obstructive pulmonary disease—COPD (↑—increased; ↓—decreased).