['Although epirubicin, an anthracycline drug, is widely used to treat hepatocellular carcinoma, its therapeutic efficacy is disappointing. Thus, the efficacy of epirubicin may be improved when combined with other drugs. This study investigated the therapeutic potential of combination of progesterone and epirubicin in the treatment of the human hepatoma cell line HA22T/VGH and the possible mechanisms through which this combination might induce apoptosis.', 'HA22T/VGH cells were treated without or with 25\xa0μM progesterone and/or 0.5\xa0μM epirubicin and analyzed for oxidative stress, redox status, Fas/FasL expression, caspase activity, and apoptosis.', 'HA22T/VGH cells treated with epirubicin increased the production of reactive oxygen species and nitric oxide, the expression of Fas, FasL, and Fas-associated death domain, and the activities of caspase-8 and caspase-3. Epirubicin treatment also decreased glutathione resulting in the induction of apoptosis. Treatment with progesterone alone increased nitric oxide production, but it did not affect the other parameters. However, when HA22T/VGH cells were treated with progesterone and epirubicin, the effects of epirubicin were enhanced.'] Does progesterone augment epirubicin-induced apoptosis in HA22T/VGH cells by increasing oxidative stress and upregulating Fas/FasL?