Prox1CreERT2 mice express a tamoxifen-inducible cre/ERT2 fusion gene under the control of the prospero homeobox 1 (Prox1) gene promoter and enhancer elements. Prox1, or prospero homeobox 1, encodes a transcription factor that is necessary for the specification and development of lymphatic vessels. PROX1 functions as a key regulatory protein in neurogenesis and is also expressed in cardiomyocytes, skeletal muscle, eye lens, liver, pancreas, megakaryocytes, and the lymphatic system. It has also been shown to be involved in the regulation of the circadian rhythm and is involved in tumorigenesis. Heterozygous mice are viable and fertile, the donating investigator did not produce a homozygous colony. When transgenic mice are bred with mice containing loxP-flanked sequences, tamoxifen-inducible Cre-mediated recombination will result in deletion of loxP-flanked sequences in Prox1-expressing cells. Variable recombination occurs in the endothelium of large veins, which transcribe but do not translate PROX1. When Prox1CreERT2 transgenic mice are bred to mTmG mice (Stock No. <a href="https://www.jax.org/strain/007676">007676</a>), which express tdTomato prior to Cre-mediated deletion of a STOP cassette and express EGFP after Cre-mediated deletion of a STOP cassette, all tissues expressing Prox1, including all lymphatic endothelial cells, liver cells, skeletal muscle, cardiomyocytes, lens of the eye, some pancreatic cells, and some neural progenitors, are labeled with EGFP in resulting offspring following tamoxifen administration. The donating investigator reports no recombination in the absence of tamoxifen. Of note, Prox1-Cre-ERT2 knock-in mice (Stock No. <a href="https://www.jax.org/strain/022075">022075</a>) have a IRES-cre/ERT2 fusion protein sequence inserted into exon 2 of the endogenous Prox1 gene which may affect Prox1 gene expression and may limit cre/ERT2 gene expression.

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Prox1CreERT2 mice express a tamoxifen-inducible cre/ERT2 fusion gene under the control of the Prox1 promoter. This strain allows temporally controlled deletion of floxed genes in all tissues expressing Prox1, including all lymphatic endothelial cells, liver cells, skeletal muscle, cardiomyocytes, lens of the eye, some pancreatic cells, and some neural progenitors.