Resistance in response to E2F-1 expression in the HCT116 PUMA-/- cell line compared to the HCT116 PUMA+/+ cell line by cell viability assay. Both floating and adherent cells were harvested, counted, and scored at indicated time points. Viability was assessed using the trypan blue exclusion method. Results are expressed as the percent viable cells at each point and values represent the means ± SD (bars) of three independent experiments. A. HCT116 PUMA-/- and HCT116 PUMA+/+ cell lines were treated by infection with Ad-LacZ or Ad-E2F-1 at indicated MOI. The viability was assessed at day 4 after virus infection. B. Time course of cell viability of HCT116 PUMA-/- and HCT116 PUMA+/+ cells in response to Ad-LacZ or Ad-E2F-1 infection at MOI of 50.