Figure 5. Expression of a therapeutic gene from conventionally and Cre-loxP cloned promoters and analysis of theraputic index. NCI H69 cells were transiently transfected with the therapeutic gene HSVTK cloned by the conventional and Cre-loxP based method with the SV40 and INSM1 promoters. 24 hrs after transfection the cells were incubated with ganciclovir and cell survival was measured after 5 days. The control is a plasmid without HSVTK. The values for each plasmid is normalised to the samples without addition of ganciclovir (defined as a relative survival of 1). The data shown is mean of 2 (INSM1) or 4 (SV40) individual experiments with S.E.M.