In vitro enhanced protein synthesis inhibition activity of H19-DTA-P4-DTA in human bladder carcinoma cell lines: Tumor growth inhibition activity of the H19-DTA, P4-DTA and H19-DTA-P4-DTA vectors in T24P (A-B) and HT-1376 (C-D) cells was measured as a reduction of LucSV40 activity. Cells were cotransfected with 2 μg of LucSV40 and the indicated concentrations of the DTA expressing vectors, or with LucSV40 alone. Transfection experiments were stopped after 48 hours and luciferase activity was assessed. The decrease in LucSV40 activity was determined by comparison to the same cell type transfected with LucSV40 alone as a measure for cytotoxicity. The diverse effect of each vector at the lowest plasmid transfected concentration is indicated (B, D).