Strain Name:


Stock Number:



Awaiting Transfer from the Donor

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K-rasFSF-G12D mice allow conditional, sequential expression of the oncogenic G12D mutant form of Kras (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) following Flp recombinase-mediated excision of a FRT-flanked Stop cassette.


Strain Information

Type Congenic; Mutant Strain; Targeted Mutation;
Additional information on Genetically Engineered and Mutant Mice.
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Additional information on Congenic nomenclature.
Specieslaboratory mouse
Donating InvestigatorDr. Tyler Jacks,   Massachusetts Institute of Technology

This K-rasFSF-G12D strain carries an FRT-flanked Stop cassette in intron 1 of the Kras (v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog) gene. Flp recombinase-mediated excision of the Stop cassette enables conditional, sequential expression of the oncogenic G12D mutant form of the gene. When recombined in various tissues, the phenotype is anticipated to be the same as that seen with tissue-specific Cre-mediated recombination in the K-ras LSL strain (see Stock No. 008180).

An Frt-STOP-Frt (FSF) cassette was inserted into the Sal I site in intron 1 of the targeted gene, which also carries a G->D point mutation in codon 12. A puromycin resistance gene is flanked by FRT sites, 5' of the STOP element, and reads in the opposite orientation to that of the targeted locus. The mutation was created using C57BL/6-derived v26.2 embryonic stem (ES) cells. Subsequent crosses with other strains (major alleles now bred away) were carried out. This line was backcrossed to C57BL/6J for 11 generations by the donating lab.

Control Information

   Wild-type from the colony
  Considerations for Choosing Controls

Related Strains

Strains carrying   Krastm5Tyj allele
008653   B6;129-Krastm5Tyj/J
View Strains carrying   Krastm5Tyj     (1 strain)

Strains carrying other alleles of Kras
002674   129-Krastm1Tyj/J
008185   129S/Sv-Krastm3Tyj/J
008180   129S/Sv-Krastm4Tyj/J
008179   B6.129S4-Krastm4Tyj/J
019104   B6N.Cg-Krastm4Tyj/CjDswJ
View Strains carrying other alleles of Kras     (5 strains)


Phenotype Information

View Related Disease (OMIM) Terms

Related Disease (OMIM) Terms provided by MGI
- Potential model based on gene homology relationships. Phenotypic similarity to the human disease has not been tested.
Bladder Cancer   (KRAS)
Breast Cancer   (KRAS)
Cardiofaciocutaneous Syndrome 2; CFC2   (KRAS)
Gastric Cancer, Hereditary Diffuse; HDGC   (KRAS)
Lung Cancer   (KRAS)
Noonan Syndrome 3; NS3   (KRAS)
Pancreatic Cancer   (KRAS)
Schimmelpenning-Feuerstein-Mims Syndrome; SFM   (KRAS)
View Mammalian Phenotype Terms

Mammalian Phenotype Terms provided by MGI
      assigned by genotype

The following phenotype information may relate to a genetic background differing from this JAX® Mice strain.


        involves: 129S4/SvJae * C57BL/6   (conditional)
  • tumorigenesis
  • increased lung tumor incidence
    • following administration of a flp-expressing adenovirus or lentivirus   (MGI Ref ID J:172206)
View Research Applications

Research Applications
This mouse can be used to support research in many areas including:

Cancer Research
Genes Regulating Growth and Proliferation

Research Tools
FLP-FRT System
      FRT-flanked Sequences

Genes & Alleles

Gene & Allele Information provided by MGI

Allele Symbol Krastm5Tyj
Allele Name targeted mutation 5, Tyler Jacks
Allele Type Targeted (Floxed/Frt)
Common Name(s) K-ras FSF; K-rasFSF-G12D;
Mutation Made ByDr. Tyler Jacks,   Massachusetts Institute of Technology
Strain of OriginC57BL/6
ES Cell Line NameV26.2
ES Cell Line StrainC57BL/6
Gene Symbol and Name Kras, v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog
Chromosome 6
Gene Common Name(s) AI929937; C-K-RAS; CFC2; K-RAS2A; K-RAS2B; K-RAS4A; K-RAS4B; K-ras; KI-RAS; KRAS1; KRAS2; Kirsten rat sarcoma oncogene 2, expressed; Kras-2; Kras2; NS; NS3; RASK2; c-Ki-ras; expressed sequence AI929937; p21;
Molecular Note This allele has a FRT-STOP-FRT cassette in intron 1 of the oncogenic form of the v-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog gene (G12D mutation). Before expression of enhanced Flp (FLPe) or mouse codon-optimized FLP (FLPo) recombinase, the allele is not expressed due to the transcriptional STOP cassette. Following introduction of the recombinase, the FRT sites are recombined and the STOP cassette is removed resulting in expression of the mutant Kras transcript and protein. [MGI Ref ID J:140469]


Genotyping Information

Helpful Links

Genotyping resources and troubleshooting


References provided by MGI

Additional References

Krastm5Tyj related

Jacks T. 2008. Generation of a conditional mutant Kras allele MGI Direct Data Submission :.  [MGI Ref ID J:140469]

Lee CL; Moding EJ; Huang X; Li Y; Woodlief LZ; Rodrigues RC; Ma Y; Kirsch DG. 2012. Generation of primary tumors with Flp recombinase in FRT-flanked p53 mice. Dis Model Mech 5(3):397-402. [PubMed: 22228755]  [MGI Ref ID J:180576]

Snyder EL; Watanabe H; Magendantz M; Hoersch S; Chen TA; Wang DG; Crowley D; Whittaker CA; Meyerson M; Kimura S; Jacks T. 2013. Nkx2-1 represses a latent gastric differentiation program in lung adenocarcinoma. Mol Cell 50(2):185-99. [PubMed: 23523371]  [MGI Ref ID J:198227]

Youn JI; Kumar V; Collazo M; Nefedova Y; Condamine T; Cheng P; Villagra A; Antonia S; McCaffrey JC; Fishman M; Sarnaik A; Horna P; Sotomayor E; Gabrilovich DI. 2013. Epigenetic silencing of retinoblastoma gene regulates pathologic differentiation of myeloid cells in cancer. Nat Immunol 14(3):211-20. [PubMed: 23354483]  [MGI Ref ID J:193480]

Young NP; Crowley D; Jacks T. 2011. Uncoupling Cancer Mutations Reveals Critical Timing of p53 Loss in Sarcomagenesis. Cancer Res 71(11):4040-7. [PubMed: 21512139]  [MGI Ref ID J:172206]

Health & husbandry

Health & Colony Maintenance Information

Colony Maintenance

Breeding & HusbandryWhen maintained as a live colony, heterozygotes may be bred. Homozygotes die during embryogenesis.

Pricing and Purchasing

Pricing, Supply Level & Notes, Controls


This strain is currently Awaiting Transfer from the Donor.

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Control Information

   Wild-type from the colony
  Considerations for Choosing Controls
  Control Pricing Information for Genetically Engineered Mutant Strains.

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The Jackson Laboratory has rigorous genetic quality control and mutant gene genotyping programs to ensure the genetic background of JAX® Mice strains as well as the genotypes of strains with identified molecular mutations. JAX® Mice strains are only made available to researchers after meeting our standards. However, the phenotype of each strain may not be fully characterized and/or captured in the strain data sheets. Therefore, we cannot guarantee a strain's phenotype will meet all expectations. To ensure that JAX® Mice will meet the needs of individual research projects or when requesting a strain that is new to your research, we suggest ordering and performing tests on a small number of mice to determine suitability for your particular project.
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