SMAD3 and infection: In the current study, using GFP fluorescent intensity measurements (for Ad-GFP, Ad-FoxO3, and Ad-Smad3/Ad-FoxO3 cells, all containing IRES elements that precede the GFP coding sequence), we determined Ad-infection efficiencies between 55% and 65% between 24 and 72 h (data not shown).