Figure 4

Evaluation of cytotoxicity in 4 T1 cells treated with 5-FU and then infected with SFV. (a) Schematic representation of the experiment. 4 T1 cells were pretreated with high (130 μg ml⁻¹) or low (13 μg ml⁻¹) doses of 5-FU for 2 h or 2 days and then infected with SFV/EGFP particles. (b) 4 T1 cells treated with 5-FU for 2 h and infected with SFV/EGFP particles (solid lines). The dotted lines (red) show the controls: cells treated with 5-FU for 2 h and then incubated in complete medium for 5 days. The dashed line (green) shows the cells infected with SFV/EGFP particles. (c) 4 T1 cells treated with 5-FU for 2 days and infected with SFV/EGFP particles (solid lines). The dotted lines (red) show the controls: cells treated with 5-FU for 2 days (day 0–2) and then incubated in complete medium for further three days. An MTT cell viability assay was performed every day for 5 days. The diagrams show the cytotoxic effects of 5-FU and SFV/EGFP, which are expressed as the percentage of viable cells relative to the untreated cells. Arrows indicate the beginning of drug treatment (5-FU) and the day of infection (SFV). Error bars show the standard error of three experiments. Fluorescent images demonstrate the efficiency of SFV/EGFP expression on the day after infection of 5-FU pretreated 4 T1 cells.