HepG2 human hepatoma cells (HB-8065; ATCC, Manassas, VA) were cultured in MEM (ATCC) with 10% FBS (Invitrogen, Carlsbad, CA), 4 mM glutamine (Thermo Scientific Hyclone, Waltham, MA) and 1X Penicillin and Streptomycin (Thermo Scientific Hyclone) on cell bind surface plates (Corning Inc, Corning, NY) at 37C. For transient transfection assays 8 × 105 cells were seeded per well in 6-well cell binding surface plates. 24 h after seeding, cells were transfected in serum free media with 2 μg of test DNA, along with 140 ng of CMV-galactosidase plasmid (Clontech, Mountain View, CA) and 1.2 μg of pUC19 DNA, using 3 μl Fugene HD (Roche, Indianapolis, IN). Complete medium was added 6 h after addition of DNA and cells were cultured for another 24 h. Cells were harvested 30 h after addition of DNA by scraping into ice-cold 1X PBS, pelleted by centrifugation and suspended in 100 μl of 1X Reporter lysis buffer (Promega, Madison, WI). Cell extracts were prepared by three repeated cycles of freeze-thawing followed by centrifugation at 16,000 × g for 1 min. Luciferase assays were carried out
