Cell killing potency of RGD modified viruses in vitro. Viruses with RGD modification in the capsid display effective killing of colorectal cancer cell lines. Cells were infected with replication competent (WT-RGD, WT-RGDK, WT) or non-replicating (Ad5luc1) viruses and the cell killing potency was assessed with the MTS assay. Data are presented as relative cell viability normalized to mock (growth medium) infected cells. Each data point represents the mean of six replicates ± SEM.