Metabolic labeling of HepG2 cells with 75selenite indicated the expression of more than four selenoproteins in the 80 to 45 kDa range and more than four selenoproteins in the 24 to 14 kDa range. Although there were no significant changes in the total protein content, determined by the method of BioRad, the densitometric analysis of the autoradiogramms showed a reduced expression of all labeled selenoproteins in the cell lysates of HepG2 after cytokine treatment for 24 hours. A stronger reduction was observed after treatment with Il-1beta than with IFNgamma. Moreover, the inhibitory effects were more significant for those selenoproteins in the higher molecular mass range. Our data on the inhibition of selenoprotein synthesis and on repression of SeP promoter activity show that the expression of selenoproteins, especially of SeP, is influenced by acute phase reaction and pro-inflammatory reactions.