This transgenic strain expresses Cre under the control of the Lck (lymphocyte protein tyrosine kinase) promoter, enabling thymocyte-specific excision of loxP-flanked sequences of interest. Homozygous mice are viable and have no major defects. When crossed with floxed Galnt13 mice (see Stock No. <a href="https://www.jax.org/strain/006896">006896</a>), excision occurs at high efficiency in thymocytes. Splenic CD4+ T cells show excision at somewhat lower rates (66-83%). 
 The Lck gene is primarily expressed by T lymphocytes where it phosphorylates tyrosine residues of proteins involved with intracellular signaling pathways. Associating with CD4 and CD8, LCK is part of a cascade of responses to antigen that control the proliferation and activation of T cells. It plays a key role in the selection and maturation of developing T-cells in the thymus and in the activity of mature T-cells.
 <a href="https://www.jax.org/research-and-faculty/resources/cre-repository/characterized-cre-lines-jax-cre-resource">View</a> cre expression characterization.

This transgenic strain expresses Cre under the control of the lymphocyte protein tyrosine kinase promoter, enabling thymocyte-specific excision of loxP-flanked sequences of interest. The Lck gene is primarily expressed by T lymphocytes and it plays a key role in the selection and maturation of developing T-cells in the thymus and in the activity of mature T-cells.
 In <a href="https://www.ncbi.nlm.nih.gov/pubmed/30659012">Goodwin et al. 2019 Genome Res 29:494</a>, it was discovered that Stock No. 003802 has more than 20 transgene copies integrated on chromosome 11 [41,490,714 (build mm10)]. This study reports that no gene/locus was disrupted.

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