Glucocorticoids induce a Na+ absorbing phenotype in airway epithelium by invoking the expression, assembly and membrane recruitment of epithelial Na+ channel subunits. This effect is not absolute, however, and may be further augmented by hormones such as insulin. Here, we investigated the potential for the mammalian target of rapamycin (mTOR), a kinase involved in insulin signalling, to modulate dexamethasone (Dex)-induced expression of the aENaC subunit. H441 cells cultured under serum-free conditions were transfected with N-Flag-Rheb, a specific G-protein activator of mTOR, and a luciferase reporter gene containing 2.3kb of the proximal aENaC promoter. Neither Rheb nor the mTOR inhibitor, rapamycin, affected the basal expression of the reporter gene, however, Rheb augmented the Dex-evoked expression by approximately 3-fold (P<0.01; n=4). Rapamycin antagonised the effect of Rheb without altering the activity induced by Dex. Moreover, mutation of the glucocorticoid response element in the aENaC promoter entirely abolished the Dex and Dex/Rheb induction of the reporter. We conclude that activation of the mTOR pathway augments glucocorticoid-driven aENaC transcription.