The mRNA expression of p16 (INK4a) in COPD+EPCs and COPD+P5091 groups were decreased (p < 0.001) when compared with COPD group, but still higher than the control group (Figs. 3, 4, 5, 6B–D). The gene discussed is CDKN2A; the disease is chronic obstructive pulmonary disease.