Figure 3.

Autoregulation of the xC/EBPα promoter. The three xC/EBPα promoter constructs, –1131/+41, –634/+41 and –321/+41, were co-transfected into Hep3B or A6 cell lines along with recombinant plasmid DNA driving the expression of either xC/EBPα (+α), the LAP form of xC/EBPβ (+β) or the pCS2+ vector (+vec). The relative luciferase activity obtained using the promoter-less pGL2-Basic vector, in the absence or the presence of the various pCS2+ plasmids, was subtracted from the corresponding values obtained using the xC/EBPα promoter constructs. The normalised activity for each of these promoter constructs alone (–) has arbitrarily been assigned as 1, with those obtained in the presence of the co-transfected expression plasmids being shown as fold induction with respect to this value. Each value represents the mean ± SD from three to four independent experiments.