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. 2005 Mar 22;33(5):e51. doi: 10.1093/nar/gni051

Figure 2.

Figure 2

Operation of the Cre/loxP-dependent, tetracycline inducible transgenic system. (A) Mice that are homozygous for the targeted insertion of the conditional rtTA-IRES-EGFP bicistronic transgene at ROSA26 can be bred with double transgenic mice that carry a tissue-specific Cre transgene and a doxycycline-inducible rtTA-dependent tet-O-GENE responder line. A total of 25% of the pups will be triple transgenic (SpecPromoterCreTg/+, ROSA26-STOP-rtTA-IRES-EGFPTg/+, tet-O-GENETg/+). (B) In cells that do not express Cre, neither rtTA nor EGFP protein is generated; therefore, the tet-O-GENE is silent. (C) In Cre-expressing cells, rtTA and EGFP expression is turned on. However, in the absence of an inducer (e.g. doxycycline), rtTA cannot activate the expression of the tet-O-GENE target. Addition of doxycycline results in the formation of an active transactivator and expression of the target gene. In the present study, VEGF-A-164 was induced either ubiquitously or nervous system or podocyte specifically in the presence of doxycycline.