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. Author manuscript; available in PMC: 2010 Feb 12.
Published in final edited form as: Trends Mol Med. 2003 Oct;9(10):421. doi: 10.1016/j.molmed.2003.08.005

Figure 2.

Figure 2

Binary approaches to amplify activity of weak promoter. (a) Two-step transcriptional amplification. The specific promoter drives expression of a synthetic transcriptional activator, GAL4-VP16, which in turn binds to and activates the GAL4 responsive promoter of the reporter or therapeutic gene. Multiple GAL4-VP16 activators work in concert to synergistically activate transcription of the downstream gene (denoted by upward sweeping arrow). (b) Cre-mediated activation of gene expression. Cre recombinase expression is regulated by a tissue- or cancer-specific promoter. Activation of transgene expression is induced by removal of the translational inhibition sequence via a Cre-specific recombination between the two loxP sites.