Copyright information:Taken from "Glutathione S-transferase omega in the lung and sputum supernatants of COPD patients"http://respiratory-research.com/content/8/1/48Respiratory Research 2007;8(1):48-48.Published online 6 Jul 2007PMCID:PMC1939846. compared to non-smokers and stage IV COPD (p = 0.009). The post-hoc comparison was significant at 0.05 level between non-smokers and stage I-II COPD (*). B. The mean percentage of GSTO1-1 positive macrophages was higher in severe stage IV COPD compared to smokers or COPD stage I-II (p = 0.004). The difference between non-smokers and other groups was not statistically significant. The post-hoc comparison was significant at 0.05 level between stage IV COPD and smokers and between stage IV and stage I-II COPD (*).