IGF-1 LR3 (Long R3 IGF-1): The Engineered Growth Factor Analog in Cell Culture and Biomedical Research

Introduction: Engineering a More Potent IGF-1

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Insulin-like Growth Factor-1 (IGF-1) is a 70-amino acid polypeptide hormone that serves as one of the most critical regulators of cellular growth, differentiation, and survival in vertebrate biology. However, the native peptide's utility as a research tool has always been constrained by a fundamental pharmacological limitation: its rapid sequestration by a family of six high-affinity insulin-like growth factor binding proteins (IGFBPs) that tightly regulate IGF-1 bioavailability in biological systems.

IGF-1 LR3 (Long Arginine 3-IGF-1, also written LR3-IGF-1 or LR3IGF-I) represents a rationally engineered solution to this problem. It is a recombinant 83-amino acid analog of human IGF-1 that incorporates two key structural modifications designed to dramatically reduce IGFBP binding while preserving full agonist activity at the Type I IGF receptor (IGF-1R). These modifications have made IGF-1 LR3 one of the most widely used growth factor supplements in mammalian cell culture and a valuable tool in endocrine and metabolic research.

This article provides a comprehensive examination of IGF-1 LR3's structural basis, mechanism of action, binding pharmacology, applications in cell culture and biopharmaceutical manufacturing, and its expanding role across multiple research domains.

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Structural Modifications and Molecular Properties

Native IGF-1: The Template

Native human IGF-1 is a single-chain polypeptide of 70 amino acids (molecular weight ~7.6 kDa) with a three-dimensional structure stabilized by three intramolecular disulfide bonds. It shares approximately 50% sequence homology with proinsulin and signals primarily through the Type I IGF receptor (IGF-1R), a receptor tyrosine kinase (LeRoith et al., 1995).

The N-terminal residues of IGF-1, particularly the first six amino acids, are critical determinants of IGFBP binding affinity. This region forms the primary contact surface with IGFBPs 1-6, which collectively sequester >99% of circulating IGF-1 in ternary complexes with the acid-labile subunit (ALS) and IGFBP-3 or IGFBP-5.

The Two Modifications of IGF-1 LR3

IGF-1 LR3 incorporates two distinct modifications to the native IGF-1 sequence:

1. N-terminal Extension (Long): An additional 13 amino acids (sequence: MFPAMPLLSLFVN) are appended to the N-terminus of the native sequence. This extension sterically interferes with the IGFBP binding interface at the N-terminal domain.

2. Arginine Substitution at Position 3 (R3): The glutamic acid (Glu) at position 3 of the native mature IGF-1 sequence is replaced with arginine (Arg). Since Glu3 participates directly in IGFBP recognition, this charge reversal (negative to positive) profoundly disrupts the electrostatic complementarity required for high-affinity IGFBP binding.

Resulting Molecular Properties

The combined modifications produce a polypeptide of 83 amino acids with the following characteristics:

• •Molecular weight: ~9.1 kDa (9,111-9,200 Da by mass spectrometry)
• •IGFBP binding affinity: Reduced by approximately 1,000-fold compared to native IGF-1 for IGFBP-3, IGFBP-4, and total plasma IGFBPs (Ballard et al., 1993)
• •IGF-1R binding: Retained full agonist activity at the Type I IGF receptor
• •Insulin receptor cross-reactivity: Retained ability to activate the insulin receptor (IR) at higher concentrations
• •Three disulfide bonds: Preserved from the native IGF-1 fold (Cys6-Cys48, Cys18-Cys61, Cys47-Cys52 in the native numbering)

The near-elimination of IGFBP binding is the defining pharmacological feature of IGF-1 LR3. In biological systems containing IGFBPs—which includes essentially all serum-containing media, conditioned media, and in vivo contexts—this results in dramatically increased free (bioavailable) IGF-1R ligand concentration compared to equimolar native IGF-1.

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Mechanism of Action: IGF-1R Signaling

Receptor Binding and Activation

IGF-1 LR3 exerts its biological effects primarily through activation of the Type I IGF receptor (IGF-1R), a transmembrane receptor tyrosine kinase that forms a disulfide-bonded homodimer (α₂β₂ structure). Upon ligand binding to the extracellular α-subunits, the receptor undergoes conformational change and trans-autophosphorylation of key tyrosine residues in the intracellular β-subunit kinase domains.

The activated IGF-1R recruits and phosphorylates intracellular docking proteins, primarily insulin receptor substrates 1 and 2 (IRS-1, IRS-2) and Src homology 2 domain-containing transforming protein (Shc). These adapter proteins serve as branch points for two major downstream signaling cascades ([Werner et al., 2023]()):

The PI3K/Akt/mTOR Pathway

Phosphorylated IRS-1 recruits the p85 regulatory subunit of phosphatidylinositol 3-kinase (PI3K), activating the catalytic p110 subunit. PI3K converts membrane-bound PIP₂ to PIP₃, which recruits and activates Akt (protein kinase B). Akt subsequently:

• •Activates mTORC1 (via TSC2 phosphorylation and inhibition) → promotes protein synthesis through p70S6K and 4E-BP1 phosphorylation
• •Inhibits FOXO transcription factors → suppresses atrophy-related gene programs (atrogin-1, MuRF1) (Gellhaus et al., 2023)
• •Inactivates BAD → promotes cell survival by preventing mitochondrial apoptosis
• •Activates glycogen synthase → stimulates glucose uptake and glycogen storage

The Ras/MAPK/ERK Pathway

Shc recruitment activates the Ras-Raf-MEK-ERK cascade:

• •Ras activation recruits Raf → MEK1/2 phosphorylation → ERK1/2 activation
• •ERK1/2 translocates to the nucleus where it phosphorylates transcription factors (Elk-1, c-Fos, c-Myc)
• •This pathway primarily drives cell proliferation and differentiation programs

Enhanced Potency Through IGFBP Evasion

Because IGF-1 LR3 largely evades IGFBP sequestration, a significantly higher proportion of the applied peptide remains free to engage IGF-1R. Research by Voorhamme et al. demonstrated that LR3IGF-I activates both IGF-1R and IR in HEK293 cells at concentrations at least 200-fold lower than required for insulin, and with greater receptor activation than equimolar native IGF-1 (Voorhamme et al., 2006). Ballard et al. showed that this reduced IGFBP association translates to a 5- to 10-fold greater biological potency in cultured L6 myoblasts and a 6-fold greater potency in promoting growth in rodent models (Ballard et al., 1993).

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IGFBP Binding Pharmacology: A Deeper Examination

Quantitative Binding Differences

The IGF binding protein family (IGFBP-1 through IGFBP-6) constitutes the primary regulatory mechanism for IGF bioavailability. Understanding how IGF-1 LR3 interacts—or fails to interact—with each IGFBP is essential for interpreting experimental results.

Ballard et al. (1993) conducted the definitive binding characterization, demonstrating that IGF-1 possesses approximately 1,000-fold higher affinity than LR3IGF-I toward:

• •IGFBP-3 (the major circulating carrier, forming 150 kDa ternary complexes)
• •IGFBP-4 (an inhibitory binding protein often co-localized with IGF-1R)
• •Total rat plasma IGFBPs (a composite measurement)
• •L6 myoblast-secreted binding proteins

This near-complete loss of IGFBP association has several consequences for research applications:

1. No ternary complex formation: In plasma, >75% of IGF-1 circulates in 150 kDa ternary complexes (IGF-1 + IGFBP-3 + ALS). IGF-1 LR3 cannot form these complexes, resulting in fundamentally different distribution and clearance kinetics.

2. No IGFBP-mediated modulation: IGFBPs do not merely sequester IGFs—they can also potentiate IGF activity through controlled release mechanisms. LR3IGF-I bypasses this entire regulatory layer (Hill et al., 1998).

3. Altered clearance: Without IGFBP protection, LR3IGF-I is cleared more rapidly from circulation than IGFBP-bound native IGF-1, yet its net bioactivity is substantially greater because a much larger fraction of the administered peptide is in the free, receptor-active form.

Implications for the GH-IGF-1 Axis

Exogenous LR3IGF-I can suppress endogenous IGF-1 production through negative feedback on the growth hormone (GH)-IGF-1 axis. Dunaiski et al. (1997) demonstrated that LR3IGF-I infusion in pigs decreased plasma GH concentrations by 23%, GH pulse area by 60%, and suppressed endogenous IGF-I and IGFBP-3 levels (Dunaiski et al., 1997). This negative feedback represents an important consideration in long-term in vivo experimental design.

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Applications in Cell Culture and Biopharmaceutical Manufacturing

The Primary Use Case

Perhaps the most impactful application of IGF-1 LR3 has been as a cell culture media supplement for mammalian cell lines used in recombinant biopharmaceutical production. The peptide was, in fact, specifically engineered for this purpose.

In conventional serum-supplemented cell culture, native IGF-1 in serum provides growth and survival signals through IGF-1R. However, serum lot-to-lot variability creates inconsistency in manufacturing processes. In serum-free and chemically defined media—now standard in GMP biopharmaceutical production—exogenous growth factors must be supplied directly.

IGF-1 LR3 offers critical advantages in this context:

• •Reduced concentration requirements: Because it is not sequestered by IGFBPs (which are present even in conditioned media from autocrine/paracrine secretion), effective concentrations are dramatically lower than for native IGF-1 or insulin
• •Cost efficiency: Effective at concentrations 200-fold lower than insulin for equivalent growth support (Voorhamme et al., 2006)
• •Superior consistency: IGFBP-independent activity eliminates a variable that differs between cell lines, passages, and culture conditions
• •Broad cell line compatibility: Demonstrated efficacy in CHO (Chinese Hamster Ovary), HEK293, NS0, Sp2/0, and other standard production cell lines

Serum-Free Culture of HEK293 Cells

Voorhamme et al. (2006) provided a detailed mechanistic comparison of LR3IGF-I, native IGF-I, and insulin in serum-free HEK293 culture. Key findings included:

• •LR3IGF-I activated both IGF-1R and IR in a dose-responsive manner
• •The level of receptor activation at equivalent concentrations was greater for LR3IGF-I than for either insulin or native IGF-I
• •This enhanced activation correlated with superior growth support and cell viability
• •The authors attributed the enhanced potency to the combination of direct IGF-1R activation plus freedom from IGFBP sequestration

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Research Applications Beyond Cell Culture

In Vivo Metabolic and Growth Studies

A substantial body of research has utilized IGF-1 LR3 as a pharmacological tool to investigate IGF-1 biology in the absence of IGFBP confounding.

Growth and Anabolic Effects: Tomas et al. (1996) compared IGF-I and LR3IGF-I administered by injection and continuous infusion in rodent models. Continuously infused LR3IGF-I was 1.5- to 2-fold more potent than IGF-I for changes in body weight gain, visceral organ weights, and feed conversion efficiency. Notably, LR3IGF-I maintained its potency advantage even when administered by injection rather than continuous infusion (Tomas et al., 1996).

Organ-Specific Effects: Conlon et al. (1995) investigated LR3IGF-I in guinea pigs and found that while overall body weight gain was not significantly increased, the fractional weights of adrenals, gut, kidneys, and spleen were significantly elevated, indicating tissue-selective anabolic effects independent of IGFBP-mediated distribution (Conlon et al., 1995).

Species-Specific Responses: Intriguingly, species differ in their response to LR3IGF-I. While rodents show robust growth stimulation, pigs paradoxically show decreased growth with LR3IGF-I—likely due to suppression of the GH-IGF-1 axis that, in pigs, may be more critical for overall growth than the direct IGF-1R activation provided by the analog (Dunaiski et al., 1997).

Embryonic Development Research

Prelle et al. (2001) used IGF-1 LR3 as a tool to dissect the role of IGFBPs in embryonic development. By comparing native IGF-I (which binds IGFBPs) with LR3IGF-I (which does not) in bovine embryo culture, they demonstrated that:

• •Both peptides increased blastocyst rates compared to control
• •LR3IGF-I treatment upregulated IGF-1R mRNA expression (1.3-fold), while native IGF-I downregulated it
• •The affinity for IGFBPs of the applied IGF peptide affected different developmental parameters
• •IGFBP-2 and IGFBP-3 mRNA levels responded differently to the two treatments

These findings highlighted the dual role of IGFBPs as both inhibitors and modulators of IGF signaling during preimplantation development (Prelle et al., 2001).

Neuroscience Research

Recent work by Engel et al. (2025) employed intranasal LR3-IGF-1 in a 5XFAD transgenic mouse model to investigate amyloid pathology. Seven months of intranasal LR3-IGF-1 treatment:

• •Reduced filamentous amyloid plaques in the cortex
• •Increased inert plaque forms (suggesting plaque remodeling)
• •Reduced low-molecular-weight amyloid-β oligomers
• •Enhanced microglial uptake of Aβ₁₋₄₂ peptide in vitro (BV2 cells)
• •Promoted gene pathways implicated in actin remodeling and endocytosis

However, these histopathological improvements did not translate into preserved cognitive function, illustrating the complexity of the relationship between amyloid pathology and cognitive outcomes (Engel et al., 2025).

Cultured Meat and Tissue Engineering

An emerging application area for IGF-1 LR3 is in the rapidly developing field of cultured meat production and tissue engineering. Because large-scale myoblast expansion requires serum-free, chemically defined media, IGF-1 LR3's ability to promote cell proliferation at low concentrations without IGFBP interference makes it a candidate media supplement for:

• •Satellite cell and myoblast expansion
• •Serum-free differentiation protocols
• •Large-scale bioreactor culture optimization

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Comparison with Other IGF-1 Analogs

Several other modified IGF-1 peptides exist for research purposes. Understanding how IGF-1 LR3 differs from these is important for experimental design:

IGF-1 LR3 achieves the most complete reduction in IGFBP binding while maintaining IGF-1R potency, making it the preferred research tool for IGFBP-independent IGF-1R activation.

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Stability and Handling Considerations for Research Use

Storage and Reconstitution

As a recombinant protein, IGF-1 LR3 requires appropriate handling to maintain biological activity:

• •Lyophilized form: Stable at -20°C to -80°C for extended periods; protect from moisture
• •Reconstitution: Typically dissolved in 10 mM HCl or sterile acidic buffer (pH 3-4) at concentrations of 0.1-1 mg/mL. Acidic pH maintains solubility and prevents aggregation
• •Working solutions: Dilute into culture media or physiological buffer immediately before use
• •Freeze-thaw cycles: Minimize repeated freeze-thaw; aliquot reconstituted stock into single-use volumes
• •Carrier protein: For dilute solutions (<0. Use our reconstitution calculator for precise mixing ratios.1 mg/mL), BSA (0.1-1%) is often added as a carrier to prevent adsorption to container surfaces

Stability Profile

The three disulfide bonds provide structural rigidity, but the extended N-terminal peptide may introduce some conformational flexibility. Key degradation pathways include:

• •Oxidation of methionine residues (Met in the N-terminal extension is potentially vulnerable)
• •Deamidation of asparagine residues at neutral pH
• •Aggregation at neutral or basic pH without stabilizing excipients

Researchers should verify biological activity using a cell-based proliferation assay (e.g., MCF-7 or L6 myoblasts) when using peptide that has been stored for extended periods.

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Analytical Considerations

Quality Assessment

Given its importance in GMP manufacturing and research, rigorous quality control of IGF-1 LR3 is essential:

• •HPLC purity: Reverse-phase HPLC should demonstrate >95% purity for research-grade material; >98% for cell culture-grade
• •Mass spectrometry: ESI-MS or MALDI-TOF to confirm molecular weight (~9.1 kDa) and absence of truncation products
• •Bioassay: Functional activity should be confirmed using standard cell proliferation assays. Typical ED₅₀ values are 0.3-1.5 ng/mL in serum-free MCF-7 cell proliferation assays
• •Endotoxin testing: Particularly critical for cell culture applications; LAL assay should confirm <0.1 EU/μg

For a deeper understanding of peptide quality assessment techniques, see our guide on Peptide Purity Testing Methods: HPLC and Mass Spectrometry Explained and How to Read a Certificate of Analysis (COA).

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Current Research Directions

IGFBP-Independent Signaling

One of the most active research areas involves using IGF-1 LR3 as a tool to identify IGFBP-independent effects. A 2023 review in Endocrine Reviews demonstrated that IGFBP-3 potentiates ligand-dependent activation of both IGF-1R and EGFR through sphingosine kinase 1 (SphK1) upregulation—an effect confirmed to be IGFBP-3 binding independent using LR3-IGF-1, which has very low affinity for IGFBP-3 (Baxter et al., 2023).

Metabolic Research

The intersection of IGF-1 signaling with metabolic regulation continues to generate interest. IGF-1 LR3 provides a valuable tool for investigating glucose uptake, insulin sensitivity, and AMPK pathway interactions independent of the IGFBP regulatory layer. For related metabolic research compounds, see our profiles on MOTS-c and 5-Amino-1MQ.

IGF-1R in Aging and Longevity

The IGF-1/IGF-1R signaling axis occupies a paradoxical position in aging research: reduced signaling is associated with extended lifespan in model organisms, yet IGF-1 decline in aging contributes to sarcopenia and cognitive decline. IGF-1 LR3 enables researchers to probe this paradox by providing IGFBP-independent IGF-1R activation. For broader context on aging-related peptide research, see our guide on Anti-Aging Peptides: Epitalon, FOXO4-DRI, and the Science of Longevity.

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Summary

IGF-1 LR3 stands as one of the most impactful examples of rational peptide engineering in the research tools space. By incorporating a 13-amino acid N-terminal extension and a single Glu→Arg substitution at position 3, it achieves a ~1,000-fold reduction in IGFBP binding while maintaining full IGF-1R agonist activity. This makes it indispensable for:

• •Serum-free mammalian cell culture in biopharmaceutical manufacturing
• •Mechanistic studies of IGF-1R signaling independent of IGFBP modulation
• •In vivo research requiring sustained IGF-1R activation without IGFBP confounding
• •Emerging applications in cultured meat production and tissue engineering

The extensive published literature—spanning binding pharmacology, receptor signaling, metabolic physiology, developmental biology, and neuroscience—reflects the compound's broad utility as a research tool.

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IGF-1 LR3 Supplier Pricing Comparison (Live Data — 2026)

IGF-1 LR3 is available across 30+ listings from verified research suppliers tracked by Peptides.SO. Available formats include 1 mg vials (standard research format) and 100 mcg "receptor grade" preparations for high-sensitivity binding assays.

*Data sourced from Peptides.SO live listings, August 2026. Prices subject to change. All products are for Research Use Only (

References

• •PMID: 42395176
• •PMID: 39679943
• •PMID: 19446281

RUO).*

> Sourcing note: IGF-1 LR3 is sold in two distinct grades. Standard research-grade (1 mg vials at $15–50/mg) is suitable for most cell culture, animal, and in vitro receptor assays. Receptor-grade IGF-1 LR3 (often labeled "Receptor Grade" from manufacturers like Biotech Peptides) undergoes additional purification steps — typically ≥99% purity by HPLC and confirmed absence of endotoxin — suitable for sensitive receptor binding, radioligand displacement, and cell signaling assays where trace contaminants could activate off-target pathways. Confirm formulation: standard IGF-1 LR3 is typically formulated without any carrier proteins; some vendors offer carrier-free versions; receptor-grade variants may include 0.1% BSA as a stabilizer.

See the IGF-1 LR3 peptide page for real-time pricing, current stock status, and supplier comparison across all active listings.

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Frequently Asked Questions: IGF-1 LR3 Research

Q: What is the key functional difference between IGF-1 and IGF-1 LR3 in research applications?

Standard IGF-1 binds avidly to IGF binding proteins (IGFBPs), which are present in serum and most biological fluids at concentrations that sequester a significant fraction of exogenous IGF-1, reducing its receptor-accessible bioactivity. IGF-1 LR3's 13-amino-acid N-terminal extension and Arg³ substitution reduce IGFBP binding affinity by >100-fold while preserving IR/IGF-1R receptor binding, making it functionally more potent in serum-containing systems and in vivo — a key reason it's the preferred form for cell culture supplementation where IGFBP interference would otherwise compromise dosing accuracy.

Q: Why is IGF-1 LR3 used in bioreactor/bioprocess applications?

IGF-1 LR3 replaced insulin and standard IGF-1 as the primary growth factor supplement in many industrial cell culture applications (CHO, HEK293, hybridoma production) because its IGFBP-resistance maintains bioactivity throughout long fermentation runs where IGFBPs accumulate in conditioned media. It also permits serum-free or reduced-serum culture at lower concentrations than standard IGF-1, reducing cost per liter of cell culture medium.

Q: What concentrations are used in typical in vitro IGF-1 LR3 experiments?

For proliferation and survival assays in most cell types: 10–100 ng/mL (1.3–13 nM) is the typical starting range. For serum-free suspension culture (CHO, HEK293): 1–10 µg/mL. For receptor binding and competition assays: sub-nM concentrations. For in vivo rodent experiments: 0.1–1 mg/kg body weight per injection. All concentrations should be independently validated for each cell line, as receptor expression levels determine dose-response relationships.

Q: Is IGF-1 LR3 better than IGF-1 DES for myoblast and muscle cell research?

They have different primary applications. IGF-1 DES (Des(1-3)-IGF-1) also has reduced IGFBP binding, but its N-terminal truncation makes it preferentially active at the periphery of tissues where IGFBP concentrations differ. For most cell culture applications, IGF-1 LR3 is the standard choice due to its extensively published bioactivity data, commercial availability, and longer half-life compared to DES. DES has been used in some muscle satellite cell research, but the literature base for LR3 in myoblast proliferation is larger.

Q: What is the proper reconstitution protocol for IGF-1 LR3?

Lyophilized IGF-1 LR3 should be reconstituted in sterile, carrier-protein-containing solutions to prevent adsorption to container surfaces. The standard protocol: add 0.1% BSA in sterile PBS or sterile acetic acid (1 mM) as the initial reconstitution vehicle, then dilute to working concentration in culture medium. Do not reconstitute directly in plain water without BSA — IGF-1 LR3 will adsorb to glass/plastic and apparent concentration will be lower than intended. Reconstituted stocks should be aliquoted and stored at -80°C; avoid repeated freeze-thaw cycles. See the reconstitution guide for general peptide handling protocols.

Q: Are there IGF-1 LR3 alternatives to consider for specific research questions?

Yes — the choice depends on the research question. For systemic in vivo GH axis studies: Sermorelin or Tesamorelin work upstream at the GHRH/GH level. For IGFBP-independent IGF signaling: Des(1-3)-IGF-1 offers a shorter half-life that may be useful in kinetic studies. For IGF-1R-specific pharmacological studies: some research uses selective IGF-1R antibodies or small-molecule IGF-1R inhibitors rather than IGF-1 analogs. IGF-1 LR3 remains the preferred choice when potency, IGFBP-resistance, and a large published literature base are prioritized.

> Research Use Only. All listed material is sold strictly for laboratory research purposes. Not for human or animal administration.

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Key References

1. Ballard FJ, et al. (1993). Effects of interactions between IGFBPs and IGFs on the plasma clearance and in vivo biological activities of IGFs and IGF analogs. Growth Regul, 3(1):40-4. PubMed

2. Tomas FM, et al. (1996). Superior potency of infused IGF-I analogues which bind poorly to IGF-binding proteins is maintained when administered by injection. J Endocrinol, 150(1):77-84. PubMed

3. Conlon MA, et al. (1995). Long R3 insulin-like growth factor-I infusion stimulates organ growth but reduces plasma IGF-I, IGF-II and IGF binding protein concentrations in the guinea pig. J Endocrinol, 146(2):247-53. PubMed

4. Dunaiski V, et al. (1997). Long [R3] insulin-like growth factor-I reduces growth, plasma growth hormone, IGF binding protein-3 and endogenous IGF-I concentrations in pigs. J Endocrinol, 155(3):559-65. PubMed

5. Hill RA, et al. (1998). Regulation of insulin-like growth factor I bioactivity in vivo: further characterization of an IGF-I-enhancing antibody. Endocrinology, 139(3):1000-9. PubMed

6. Prelle K, et al. (2001). IGF-I and long R(3)IGF-I differently affect development and mRNA abundance for IGFBPs and type I IGF receptors in in vitro produced bovine embryos. Endocrinology, 142(3):1309-16. PubMed

7. Voorhamme D, et al. (2006). LONG R3IGF-I as a more potent alternative to insulin in serum-free culture of HEK293 cells. Mol Biotechnol, 34(2):201-4. PubMed

8. Engel MG, et al. (2025). Intranasal long R3 insulin-like growth factor-1 treatment promotes amyloid plaque remodeling in cerebral cortex but fails to preserve cognitive function in male 5XFAD mice. J Alzheimers Dis, Jan. PubMed

9. Gellhaus B, et al. (2023). Therapeutic Consequences of Targeting the IGF-1/PI3K/AKT/FOXO3 Axis in Sarcopenia: A Narrative Review. Cells, 12(24):2787. PubMed

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This article is provided for educational and research reference purposes only. All compounds discussed are intended for laboratory research use only (RUO). Researchers should consult institutional guidelines and applicable regulations before incorporating any research compounds into experimental protocols.

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Further Reading:

• •IGF-1 (Insulin-Like Growth Factor 1): Complete Research Profile — Structure, Signaling, and Multi-Tissue Applications
• •MGF (Mechano Growth Factor / IGF-1Ec): Complete Research Profile — The Mechanosensitive IGF-1 Splice Variant in Muscle, Neural, and Cardiac Research (2026)
• •Sermorelin: The Original GHRH Analog for Growth Hormone Research
• •PE-22-28: Complete Research Profile — Spadin Analog, TREK-1 Blocker, and Rapid-Onset Antidepressant Peptide for Nootropic Research (2026)
• •Reconstitution Calculator
• •Peptide Stack Builder