<h2 data-section-id="pdko8n" data-start="0" data-end="50">What are recombinant proteins for cell culture?</h2>
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Recombinant proteins for cell culture are biologically active growth factors, cytokines, and signaling molecules produced using recombinant DNA technology to control specific cellular functions in vitro. Growth factors such as FGF (fibroblast growth factor), EGF (epidermal growth factor), and TGF-&beta; (transforming growth factor beta) regulate cell growth, proliferation, survival, and differentiation. Cytokines including IL-2, IL-7, IL-15, and IL-21 influence immune cell activation, expansion, and function. These proteins are widely used in serum-free and chemically defined media, stem cell and iPSC culture, immune cell expansion, organoid development, hybridoma production, and cell and gene therapy workflows where precise control over cellular signaling is required.
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<h2 dir="ltr">What you will find:</h2>
&nbsp;
<ul>
<li>Includes cytokines, chemokines, growth factors, and signaling proteins to support proliferation, differentiation, and maintenance of&nbsp;mammalian cells</li>
<li>Rat, human, and mouse recombinant proteins compatible with translational research models and diverse mammalian cell culture&nbsp;</li>
<li>Optimizing cell metabolic activity, signalling pathways, and experimental reproducibility in vitro using recombinant proteins&nbsp;</li>
<li>Suitable for organoid development, expansion of cells, activation of immune cells, neuronal studies, and protein expression workflow optimization.</li>
</ul>
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<h2 data-section-id="4x59d8" data-start="1050" data-end="1118">How to choose recombinant proteins, cytokines, and growth factors</h2>
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Quality grade: RUO vs. preclinical vs. GMP
Research-use-only (RUO) proteins are suitable for most academic and industrial research applications. Preclinical-grade proteins provide enhanced documentation and quality control for studies supporting clinical development. GMP-grade proteins are manufactured under controlled quality systems with complete traceability and lot-to-lot bioactivity verification, making them appropriate for cell therapy, gene therapy, and other regulated applications.
Expression system and post-translational modifications
The production system can significantly affect protein activity. HEK293 and other mammalian expression systems preserve native human post-translational modifications such as glycosylation and phosphorylation, which are often necessary for full biological function. Bacterial expression systems such as E. coli may offer lower cost and higher yields but cannot reproduce many of these modifications.
Carrier-free formulation
Carrier-free recombinant proteins are formulated without stabilizing proteins such as bovine serum albumin (BSA). This eliminates potential experimental interference from carrier proteins and supports serum-free, animal-component-free, and GMP-compatible workflows. Carrier-free formulations are especially important when studying sensitive signaling pathways or developing clinical manufacturing processes.
Endotoxin level and purity
Endotoxins can stimulate inflammatory responses and alter cell behavior, particularly in immune cell cultures. For T-cell expansion, stem cell culture, and other sensitive applications, low-endotoxin or endotoxin-free proteins with documented purity above 95% are preferred to ensure reproducible results.
Stability format: standard vs. thermostable
Standard recombinant proteins gradually lose activity during prolonged incubation at 37&deg;C. Thermostable variants, such as engineered FGF2 formulations, maintain biological activity for longer periods and reduce the need for frequent media supplementation. These products can improve workflow efficiency in stem cell maintenance and differentiation protocols.
Storage and reconstitution
Lyophilized recombinant proteins offer extended shelf life and are typically stored frozen until use. After reconstitution, proteins should be aliquoted into single-use portions whenever possible to minimize repeated freeze-thaw cycles that can reduce activity. Proper storage conditions vary by product and should follow the manufacturer's recommendations.
<h2 data-section-id="rxnuuy" data-start="3659" data-end="3704">&nbsp;</h2>
<h2 data-section-id="1fljvas" data-start="4451" data-end="4476">Specifications context</h2>
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Modern recombinant cytokines and growth factors are available in a wide range of formats including carrier-free, low-endotoxin, animal-component-free, and GMP-grade formulations. Many GMP-grade cytokines such as IL-2, IL-7, IL-15, and IL-21 undergo lot-specific bioactivity testing using validated reference standards to ensure consistent biological performance. Mammalian-cell-expressed proteins are increasingly preferred for applications requiring native structure and maximum biological activity.
As of 2026, carrier-free, low-endotoxin recombinant proteins produced in mammalian expression systems have become the preferred choice for stem cell culture, immune cell expansion, organoid development, and advanced biomanufacturing workflows.
For basal media used alongside recombinant proteins, see Classic Media. For additional supplementation reagents, see Cell Culture Supplements &amp; Additives. Browse Mammalian Cell Culture for the broader category.
<a href="https://mbpinc.net/contact-us">Contact the expert team</a> at MBP today and get optimized recombinant proteins for your lab.

Recombinant Proteins

MSDS

Growth Factor-eFlyer

Growth Factors and Cytokines-Brochure

Growth Factors and Cytokines-FAQ

Role of Growth Factors in Cell Differentiation-Poster

Recombinant Rat IL5

Recombinant Rat IL5 Z300155 by ABM — 13 kDa E. coli, &gt;95% pure by SDS-PAGE, ED(50) ≤0.2 ng/mL with specific activity ≥6.0×106 units/mg (TF-1 proliferation), &lt;1.0 EU/µg endotoxin. Eosinophil/Th2 cytokine. Ships from MBP INC to USA, Canada, and international labs.

Organism

Family

Aliases

Gene Symbol

Gene ID

Accession Number

Source

Species

Appearance

Molecular Weight

Endotoxin Level

Purity

Formulation

Function

Reconstitution

Storage

Usage

Manufacturer

Shipping Condition

Storage Condition

Recombinant Rat IL6

Recombinant Rat IL-6 by Applied Biological Materials is expressed in E. coli with purity >95% by SDS-PAGE, endotoxin <1.0 EU/µg by LAL, ED50 20–40 ng/mL in monkey 4MBr-5 proliferation assay, and tag-free lyophilized formulation in PBS.

Recombinant Rat IL6, 10 µg

Recombinant Rat IL6, 1.0 mg

Flyer

Brochure

Recombinant Rat LIX  (CXCL5)

Recombinant Rat LIX (CXCL5) — catalog number Z300125 by Applied Biological Materials — is a tag-free, E. coli-expressed neutrophil-activating chemokine with 11 kDa molecular weight, greater than 95% purity by SDS-PAGE, endotoxin below 1.0 EU/µg by LAL, and an ED50 of 2.0–40.0 ng/mL for neutrophil chemoattraction. The lyophilized protein (UniProt P97885) is formulated in phosphate buffer with 100 mM NaCl at pH 7.5 and is used in CXCR2 signaling, neutrophil migration assays, and in vitro inflammatory models. Available from MBP in 20 µg and 1.0 mg sizes — order via <a href="https://www.mbpinc.net/quickorder">Quick Order</a> or email <a href="mailto:customerservice@mbpinc.net">customerservice@mbpinc.net</a>.

Recombinant Rat LIX  (CXCL5), 20 µg

Recombinant Rat LIX (CXCL5), 1.0 mg

Recombinant Rat TNF

Recombinant Rat TNF — Z300065 by Applied Biological Materials. E. coli-expressed, tag-free, &gt;95% pure by SDS-PAGE, 17 kDa, 157 aa, endotoxin &lt;1.0 EU/µg. ED50 20–40 ng/mL. Available in 20 µg, 100 µg, and 1.0 mg.

Recombinant Rat TNF, 20 µg

Recombinant Rat TNF, 100 µg

Recombinant Rat TNF, 1.0 mg

<h2 dir="ltr"> What Are Retroviral Control &amp; Reporter Constructs?</h2>
 Every retroviral over-expression experiment requires a matched set of control constructs to confirm that transduction was successful, the packaging system produced infectious virus at an adequate titer, and the empty vector backbone does not itself alter the measured phenotype. Retroviral control and reporter vectors use the same LTR and backbone configuration as experimental over-expression vectors. Reliable controls and reporters improve confidence in transduction and expression studies. Select the control/reporter system appropriate for your experiment.
&nbsp;
<h2 dir="ltr">What you will find:</h2>
&nbsp;
<ul>
<li data-section-id="w0hi5b" data-start="4179" data-end="4269">Retro-CMV Blank Retroviruses used as baseline controls for retroviral delivery systems</li>
<li data-section-id="ut4vdp" data-start="4270" data-end="4370">Fluorescent Reporter Retroviruses (GFP, RFP) for real-time monitoring of transduction efficiency</li>
<li data-section-id="izipmv" data-start="4371" data-end="4456">Bicistronic GFP Reporter Vectors for co-expression and experimental normalization</li>
<li data-section-id="we28ta" data-start="4457" data-end="4544">Epitope-tagged Control Vectors supporting protein detection and expression analysis</li>
<li data-section-id="47lirb" data-start="4545" data-end="4642">Stop-codon Reporter Plasmids for assessing baseline expression and vector background activity</li>
<li data-section-id="1d2i69z" data-start="4643" data-end="4735">CMV-driven control plasmids used in retroviral expression and stable cell line workflows</li>
</ul>
<h2 dir="ltr"> How to Choose Retroviral Control &amp; Reporter Constructs</h2>
 Empty Vector Backbone Matching The empty vector control must match the experimental vector in backbone, LTR configuration, internal promoter, and selection marker &mdash; for pBABE experiments, pBABE-puro empty is correct; for pLNCX2 experiments, an empty pLNCX2 vector is required. Mismatched controls introduce confounding variables. Transduction Efficiency Verification GFP-expressing retroviral controls (pBABE-GFP, pMSCV-GFP) enable real-time FACS-based quantification before proceeding with experimental constructs &mdash; Adequate efficiency is typically assessed empirically based on cell type and experimental design, ensuring that packaging and infection conditions are suitable for downstream applications. Histochemical Detection Needs pLAPSN, derived from the pLXSN backbone, expresses bacterial alkaline phosphatase (AP), detectable histochemically with substrates such as NBT/BCIP &mdash; useful when fluorescence-based detection is not available or appropriate, particularly in fixed tissue sections. In Vivo Tracking Requirements Retroviral GFP and luciferase reporter cell lines support in vivo tracking of transplanted cells in mouse models, including haematopoietic reconstitution studies and tumour xenograft experiments via bioluminescence imaging. Multiplexing Considerations Retroviral GFP reporters are compatible with red-channel markers (RFP, mCherry, tdTomato) in multiplexed imaging and FACS &mdash; ensure control and experimental constructs use spectrally distinct reporters. 
<h2> Specifications Context</h2>
 Retroviral control and reporter systems using Retro-CMV and pRetroG-CMV vectors deliver CMV-driven expression cassettes packaged as replication-incompetent retroviral particles for transduction of actively dividing mammalian cells. These systems support stable genomic integration of GFP/RFP reporters, HA-tagged constructs, bicistronic IRES-based expression formats, and empty vector controls for baseline comparison and experimental normalization. Following transduction, integrated expression is maintained through cell division under selection or reporter-based enrichment, enabling consistent gene expression analysis, functional studies, and stable cell line generation in retroviral workflows. Product availability reflects MBP's catalogue as of mid-2026. 
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<a href="https://mbpinc.net/contact-us">Contact the expert team </a>at MBP to get advanced retroviral control/reporters for your lab today.

Control/Reporter

Lentiviral Vector Amplification Protocol

AAV Infection Guideline

AAV Packaging Protocol

Selection-Drug Killing Curve

Lentivector Packaging Protocol

Lentivirus Infection Protocol

Retro-CMV Blank Retrovirus

Unit Quantity

Vector Map

Titer

Retro-CMV-GFP Retrovirus, RVP003

Retro-CMV-GFP Retrovirus

System

Retro-CMV-GFP-HA Retrovirus, RVP002

Retro-CMV-GFP-HA Retrovirus

Retro-CMV-GFP-IRES-GFP Retrovirus, RVP004

Retro-CMV-GFP-IRES-GFP Retrovirus

Retro-CMV-RFP Retrovirus, RVP005

Retro-CMV-RFP Retrovirus

<h2 dir="ltr">What Are Retroviral Cloning Vectors?</h2>
 The transfer plasmid defines the cargo, promoter, and selection strategy of a retroviral vector system. Selecting the right cloning vector backbone determines transgene expression level, integration stability across cell types, and compatibility with available packaging cell lines. Efficient vector development starts with the right cloning backbone. Choose a retroviral vector that supports your research needs.
&nbsp;
<h2 dir="ltr">What you will find:</h2>
&nbsp;
<ul>
<li data-section-id="po69uo" data-start="658" data-end="756">Retro-Combo Mix vectors for streamlined retroviral construct assembly and expression workflows</li>
<li data-section-id="5ibmf5" data-start="757" data-end="857">pRetro-E1 and pRetro-E2 plasmid backbones for retroviral vector construction and gene expression</li>
<li data-section-id="1y6pp3s" data-start="858" data-end="961">pRetro-E1-HA and pRetro-E2-His tagged vectors for protein detection and downstream characterization</li>
<li data-section-id="gs2x4g" data-start="962" data-end="1091">Retro-Easy1, Retro-Easy2, Retro-Easy-HA, and Retro-Easy-His systems for flexible construct design and expression optimization</li>
<li data-section-id="fzbhcl" data-start="1092" data-end="1178">Pack-Easy Cells for efficient retroviral packaging and vector production workflows</li>
</ul>
<h2 dir="ltr"> How to Choose a Retroviral Cloning Vector</h2>
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Backbone and Expression Architecture
Retroviral cloning vectors in the Retro-Easy and pRetro-E systems utilize CMV-driven expression cassettes for transgene expression following genomic integration. Backbone configuration influences expression consistency, cloning flexibility, and compatibility with downstream packaging workflows.
Promoter Configuration
CMV-based internal promoters provide strong, constitutive expression across a wide range of mammalian cell types. Expression levels may vary depending on the integration site and chromatin environment following retroviral integration.
Packaging Workflow Compatibility
Retroviral cloning vectors are designed for use in standard replication-incompetent packaging systems, where transfer plasmids are supplied alongside packaging components to generate infectious retroviral particles for transduction of dividing cells.
Selection and Tag Options
Vector variants include antibiotic selection markers and epitope-tagged formats (HA, His) to support downstream detection, purification, or functional validation of expressed proteins.
Insert Size Considerations
Gamma-retroviral transfer vectors generally support moderate-sized inserts suitable for most cDNA and reporter constructs, with efficiency influenced by insert length and sequence composition. 
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<h2 dir="ltr">Specifications Context</h2>
&nbsp;
Retro-Easy and pRetro-E vector systems are based on CMV-driven retroviral transfer backbones designed for stable gene delivery in actively dividing mammalian cells. Following packaging, replication-incompetent retroviral particles mediate genomic integration of the transgene, enabling stable expression across cell divisions. Available formats include untagged, HA-tagged, and His-tagged expression vectors, as well as modular backbone variants for flexible construct design. Pack-Easy Cells provide a dedicated packaging platform for efficient retroviral particle production and consistent vector output. These systems support applications in gene expression analysis, functional studies, and stable cell line generation.
&nbsp;
<a href="https://mbpinc.net/contact-us">Contact the expert team</a> at MBP and find the right Retrovirus Cloning Vectors for your lab.