PTEN and chronic obstructive pulmonary disease: The knockdown of PTEN was accompanied with the significant phosphorylation of Akt (p-Akt/total-Akt) (Fig. 5B, bottom), and enhanced the secretion of various cytokines, such as IL-6, CXCL8, CXCL10, CCL2, and CCL5 (Fig. 5C) in the cytokine array assay, all of which are known to be associated with the proinflammatory response in the pathogenesis of COPD (6).