The mRNA expression levels of the HA117 and MDR1 genes in 4T1 cells 48 h after transduction of Ad-GFP-HA117 or Ad-GFP-MDR1 as quantified by RT-PCR. The levels of HA117 and MDR1 mRNA increased significantly 48 h after transduction. The expression of GAPDH mRNA was also examined and served as a loading control. The bar graphs represent the quantification and comparison of the signal intensity of the mRNA bands on the gel. M: 50-bp DNA ladder; 1: 4T1; 2: 4T1/GFP transfectants; 3: 4T1/HA117 transfectants; 4: 4T1 cells; 5: 4T1/GFP transfectants; 6: 4T1/MDR1 transfectants. P < 0.05 ** vs. control cells, P < 0.01*** vs. control cells. This experiment was repeated at least 3 times with the same results.