KLF5 and chronic obstructive pulmonary disease: In the COPD cells, ONOO− markedly stimulated production of KLF5 (p < 0.01, Fig 8b) and the fold changes of KLF5 in the COPD group significantly increased compared to those of the control never-smoker group (p < 0.05, Fig. 8b), suggesting that COPD bronchial fibroblasts were more susceptible to KLF5 expression induced by nitrosative stress compared to control cells.