Figure 4. The expression of the 6 core genes in the lungs of COPD patients. The relative mRNA expressions of six genes in the young COPD patients and aged COPD patients were shown, including (A) NKG7, (B) CKLF, (C) LRP4, (D) MLF1, (E) GOPD3, (F) CXCL9. Results were expressed as median (P25 quartile, P75 quartile); n=16 for young COPD and n=16 for aged COPD; *P<0.05, **P<0.01, ***P<0.001. COPD, chronic obstructive pulmonary disease; NKG7, natural killer cell granule protein 7; CKLF, chemokine like factor; LRP4, LDL receptor related protein 4; MLF1, myeloid leukemia factor 1; GDPD3, glycerophosphodiester phosphodiesterase domain containing 3; CXCL9, C-X-C motif chemokine ligand 9.