Cigarette smoke extract mediated nuclear translocation of NF-κB RelA/p65 was associated with increased nuclear levels of NF-κB RelA/p65 protein in human primary small airway epithelial cells. The primary human SAEC were treated with CSE (0.5 and 1.0%), and TNF-α (10 ng/ml) for 1 hr and nuclear proteins were isolated. Twenty microgram of nuclear protein was electrophoresed on SDS-PAGE and electroblotted onto membranes. A). Western blot showing increased nuclear levels of RelA/p65 in CSE and TNF-α treated SAEC at 1 hr. B). Nuclear protein levels of NF-κB p65 were expressed as the percentage of ratio of RelA/p65 versus actin in human SAEC. Each histogram is a representative of 3 separate experiments ± SEM. *p < 0.05, #p < 0.01, and §p < 0.001 compared with control. CSE: cigarette smoke extract.