We first evaluated: (1)“ex vivo “ the EZH2, DAB2IP and H3K27me3 immunoreactivity in bronchial epithelium from COPD patients (smokers and ex-smokers), Smokers and control subjects; then we studied: (2)“in vitro”, the EZH2, DAB2IP andH3K27me3 expression in epithelial cells (normal and cancer cell line or primary epithelial cells) chronically exposed to Cigarette Smoke Extract (CSE). Here, EZH2 is linked to cancer.