Ad-Endo enhanced the cytotoxic effects of dl 1520 in GC cells. The in vitro cytotoxic effects were analyzed using the MTT cell proliferation assay. The proliferation activities of GC cells are represented as OD values at 570 nm (630 nm was used as the reference wavelength). The cytotoxic effects are represented as the inhibition rates (or inhibitory effects), and were calculated as follows: [(ODnegative control - ODexperiment)/ODnegative control] × 100%. A) The cytotoxic effects of 10 MOIs of Ad-Endo alone, 10 MOIs of dl1520 alone or the combination of the two on GC cells (one-way ANOVA, *p<0.05 compared with dl 1520 alone and p<0.01 compared with Ad-Endo alone). B~D) The cytotoxic effects of 10 MOIs of dose dl 1520 alone or in combination with increasing doses of Ad-Endo on AGS (B), MGc80-3 (C) and SGC-7901(D) GC cells (two-way ANOVA, *p<0.05, **p<0.01 compared to that of Ad-Endo at 0 MOIs). E) Ad replication in GC cells. Cells were infected 10 MOIs of dl1520 alone or in combination with 10 MOIs of Ad-Endo, and then the total Ad (Ad-Endo and dl 1520) DNA copy number was detected by real-time PCR. Ad replication is presented as the increase in the total Ad DNA copy number. The results are shown here as the fold change in the total Ad DNA copy number at the indicated time points relative to that at 0 hours post-infection with dl 1520 alone (two-way ANOVA, *p < 0.05, **p < 0.01 compared with dl 1520 alone).