Complementary oligonucleotides, to construct the sequences described in this paper, were synthesized at the University of Utah DNA/Peptide Core Facility such that when annealed they would have appropriate ends to ligate into the SalI/ BamHI sites of the dual luciferase vector, p2luc (45) . Dual luciferase constructs were prepared and their sequence was verified as described previously (46) .