NRF1 and chronic obstructive pulmonary disease: Both protein (Figure 6A‒C) and mRNA (Figure 6E and F) levels of NRF1 and p65 were significantly upregulated in COPD group and further increased in GD-COPD group but significantly downregulated in GD-T-COPD group compared to GD-COPD group, revealing that testosterone supplementation inhibited NRF1 and p65 expression in COPD.