Cell-specific expression of EGFP in four cell lines infected with recombinant adenoviral vectors. (a) Positive expression of EGFP in LOI cell lines. Ad315-EGFP infection (10 PFU/cell) induced EGFP expression in HCT-8 and HT-29 cells. (b) Negative expression of EGFP in MOI cell lines. Fluorescence images show no EGFP expression in GES-1 cells and only weak EGFP expression in HCT116 cells infected with Ad315-EGFP (10 PFU/cell).