HBx induces the COX-2 promoter in an NF-AT–dependent manner. (a) Chang liver and HepG2 cells were transfected with 0.1 μg of the luciferase-based COX-2 reporter plasmid P2-1900 (–1796 to +104) along with increasing amounts (in Chang liver) or 5 μg (in HepG2) of pSV-X. The amount of luciferase was analyzed 18 hours later, and the results were expressed as fold induction over the value without pSV-X. (b) Chang liver cells were transfected as in a with reporter plasmids containing different deletions and point mutations of the COX-2 promoter, along with 5 μg of pSV-X or pSV-hygro. The results are expressed as fold induction over the value without pSV-X for each promoter construct and are representative of four independent experiments. (c) Chang liver cells were transfected as in a with 5 μg of pSV-X or pSV-hygro and 1 μg of the dominant negative NF-AT expression vector pSH102CΔ418, an NF-AT2 wild-type (NF-ATwt) expression vector, or the empty vector pBJ5 as a negative control. The values are expressed as fold induction over the value with pBJ5 and without pSV-X. Results are representative of at least three independent experiments.