CCL5 and chronic obstructive pulmonary disease: We also examined the PTEN-knockdown model using siRNA to reduce PTEN, which resulted in increased p-Akt even under basal conditions and also enhanced the secretion of several proinflammatory cytokines, including IL-6, CXCL8, CXCL10, and CCL5, all of which are increased in the sputum of COPD patients (9, 11).