Model Description: A CreERT2-Wpre-polyA expression cassette was knocked into the Gli1 gene start codon site. Gli1 encodes a member of the Kruppel family of zinc finger proteins. The encoded transcription factor is activated by the sonic hedgehog signal transduction cascade and regulates stem cell proliferation. The activity and nuclear localization of this protein is negatively regulated by p53 in an inhibitory loop. When these Gli1-CreERT2 mice are bred with mice containing a loxP-flanked sequence of interest, tamoxifen-inducible, Cre-mediated recombination will result in deletion of the flanked sequences in Gli1 expressing cells; making them useful for studying axis patterning, proliferation, and cell fate specification of Hedgehog responding cells at different stages of embryogenesis.