Figure 6. Expression of 7 aging-related gene candidates in COPD and normal PBMCs. (A) Expression analysis of ATM, CDKN1A, CREB3L4, HIF1A, MXD1, PTPN1 and SOD2 in blood samples by qRT-PCR; data are present as 2(-ΔCт) relative to GAPDH. (B) Expression analysis of HIF1A, CDKN1A, MXD1 and SOD2 at different GOLD stages of COPD. *P <0.05; **P <0.01.