Gene transfer to human colorectal cancer cells. Adenoviral vectors targeted for αvβ integrins via Arg-Gly-Asp (RGD) modification in the HI loop (Ad5luc1RGD) or the shaft domain (AdTLRGDK) of the fiber showed enhanced gene transfer to human colorectal cancer cell lines. Cells were infected with 1000 VP/cell and luciferase activity was measured 24 hours later. Data is presented as relative light units (RLU) normalized for gene expression of Ad5 control virus AdTL. Each data point represents the mean of three replicates ± SEM.