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Inducible Systems

Inducible Gene Expression

Since 1998, ingenious targeting laboratory has incorporated inducible expression systems into hundreds of mouse models, enabling researchers to control gene activation or deletion with temporal precision through small molecule administration.

Inducible gene expression systems provide the ability to turn genes on or off at any point in the animal's life. This temporal control separates developmental requirements from adult functions, enables study of acute gene loss, and models therapeutic intervention timing for drug development.

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Why Inducible Control Matters

Overcoming Embryonic Lethality

Constitutive Knockout Limitation: Essential genes deleted from conception often cause embryonic or perinatal death, preventing adult phenotype analysis.

Inducible Solution: Induce gene deletion in adults after development completes. Study adult function of developmentally essential genes.

Distinguishing Developmental vs Adult Function

Constitutive Knockout Limitation: Lifelong gene absence conflates developmental defects with adult requirements. Phenotype may reflect developmental abnormality rather than adult function.

Inducible Solution: Delete gene in fully developed adults. Observe acute consequences separate from developmental compensation.

Modeling Therapeutic Intervention

Constitutive Knockout Limitation: Therapeutics inhibit targets in adult patients, not from conception.

Inducible Solution: Induce deletion at disease relevant timepoints. Model drug effect timing and therapeutic window.

Major Inducible Systems

Tamoxifen Inducible (CreERT2)

The most widely used inducible system for conditional gene deletion. Cre recombinase fused to mutant estrogen receptor (ERT2) is sequestered in cytoplasm until tamoxifen binding releases Cre to enter nucleus.

  • Single administration creates permanent genetic change
  • Wide variety of tissue specific CreERT2 lines available
  • Well characterized and reliable
  • Recombination occurs within days of tamoxifen administration
Learn more

F.A.S.T.™ Technology

Flexible Accelerated STOP Tetracycline Operator provides versatile inducible/reversible control enabling multiple expression modes from a single knockin allele:

  • Knockout First Mode:Initial allele functions as a null, with gene function rescued by crossing to tissue specific Cre lines
  • Inducible Expression Mode:Gene expression induced through tetracycline transactivator (tTA) lines for ectopic or tissue specific overexpression
  • Conditional Knockdown/Knockout Mode:Gene expression silenced using tetracycline trans silencer lines for tissue specific conditional knockdown
Learn more

Choosing an Inducible System

Decision framework for selecting the appropriate inducible system:

FactorTamoxifen (CreERT2)Doxycycline (Tet)
Effect permanencePermanentReversible
Target geneEndogenous floxed alleleTransgene expression
Typical useConditional knockoutTransgene regulation
Drug concernsEstrogenic effectsMicrobiome effects
Tissue specificityVia Cre promoterVia tTA/rtTA promoter
Response time3 to 5 days1 to 2 days

Tissue Specific Inducible Cre Lines

Combine tissue specificity with temporal control. Gene deleted only in specific tissue AND only after tamoxifen administration.

LineTissueApplications
Albumin CreERT2HepatocytesInducible liver knockout
Adipoq CreERT2AdipocytesInducible fat knockout
Myh6 CreERT2CardiomyocytesInducible heart knockout
Nestin CreERT2Neural progenitorsInducible neural knockout
LysM CreERT2Myeloid cellsInducible macrophage knockout

What Researchers Say

iTL produced four conditional knockout mouse models on our behalf. They have been extremely helpful and informative at all stages of the project; all the way from construct design to breeding strategies and genotyping the new mouse models. I know where to turn when the needs comes up again for another mouse project; it is certainly faster and cheaper than doing this by ourselves.

William A. Coetzee, DSc

NYU School of Medicine

Start Your Inducible Model Project

Our scientific consultants can help you select the optimal inducible system and design strategy for your research goals. From CreERT2 knockins to floxed allele optimization, we provide comprehensive technical expertise.

✦ New for 2026

Breeding Scheme Architect

Plan complex multi-allele breeding strategies, calculate expected genotype ratios, and estimate time to experimental cohorts—all before starting your project.

Visualize multi-generation breeding paths
Calculate Mendelian ratios automatically
Estimate timeline to study-ready cohorts

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Allele 1Gene-flox (conditional)
Allele 2Cre-driver (tissue-specific)
TargetHomozygous knockout

→ 3 generations to target genotype

Frequently Asked Questions

Tamoxifen inducible Cre (CreER) enables permanent genetic changes (gene deletion via LoxP recombination) with temporal control. Doxycycline inducible (Tet) enables reversible transgene expression control. CreER provides permanent effects after induction; Tet provides reversible on/off control for expression studies.

Use tamoxifen inducible for conditional gene knockout studies, lineage tracing, or when permanent changes are needed. Use doxycycline inducible for transgene expression control, reversible studies, or dose response experiments. Selection depends on whether you need permanent genetic modification or reversible expression control.

Use tissue specific promoters to drive inducible systems (e.g., Albumin CreER for liver specific inducible knockout, or Albumin rtTA for liver specific doxycycline control). This provides both spatial control (tissue specific) and temporal control (drug inducible), enabling maximum experimental precision.

Tamoxifen is typically administered via IP injection (75 to 100 mg/kg for 3 to 5 days), oral gavage (100 to 200 mg/kg), or diet (400 mg/kg chow). Doxycycline is administered in drinking water (1 to 2 mg/mL) or diet (200 to 2000 mg/kg). Dosing depends on efficiency requirements, duration, and route preference.

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