Wild-type, Bid-deficient, or TRAIL-R-deficient MEFs (10 4 ) were seeded into black clear-bottom 96-well plates (Costar) and adsorbed with reovirus in serum-free medium at room temperature for 1 h. Following incubation of cells at 37uC for 24 h, caspase-3/7 activity was quantified using the Caspase-Glo-3/7 assay (Promega).