Efficacy of ONYX-411 is specific to RB dysfunction. (a) Dose effect of ONYX-411 adenovirus treatment of ARO, DRO and BHT101 cells. Cells were infected with ONYX-411 virus at 25, 50, 100 and 200 MOIs. Cell viability was assessed 3 days post-infection by MTT assay. Values are plotted as a percentage of mock-infected controls. The data shown here are the means ± s.d. from two independent experiments with six replicates for each variable. (b) Cell viability in various ATC cell lines after ONYX-411 infection at an MOI of 50 was assessed 3 and 6 days postinfection by MTT assay. Values are plotted as a percentage of mock-infected controls. The data shown here are the mean values ± s.d. from two independent experiments with six replicates of each variable. MOI, multiplicity of infection; MTT, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide; RB, retinoblastoma.