We provide stable, bioactive human, mouse, and rat recombinant proteins including cytokines, growth factors, and chemokines. Each of our in-house manufactured proteins undergoes rigorous quality testing and has been verified to function in a relevant bioassay.  The majority of our recombinant proteins are provided in a convenient, ready-to-use liquid format with a comparable shelf-life to lyophilized proteins.


Can’t find what you’re looking for? Contact our sales team regarding custom projects or special pricing on bulk quantities.

Our expanding catalog of recombinant proteins includes cytokines, chemokines, growth factors, enzymes, adhesions molecules, and more. These proteins are tested in a variety of bioassays to ensure bioactivity. For studies that are particularly sensitive to contamination with mammalian pathogens, we also offer animal-free versions of many of our recombinant proteins. Like our carrier-free formats, these proteins do not contain any carrier proteins; however, the animal-free products are produced in animal-free media with equipment that is free of all animal components. Browse our recombinant proteins groups below!

Prior to performing bioassay validation and stability testing, we test each recombinant protein for product purity and quantification. In the table below you can find examples of the attributes tested, the test performed, and some acceptance criteria used to ensure that our customers are confident they are receiving the highest quality reagents.

Parameter Testing


SDS-PAGE, FPLC, (>95%)



Molecular Weight

DTT-reduced and non-reduced SDS-PAGE

Microbiological Control

0.2 μm Filtration

Endotoxin Level

LAL Assay (<0.1 ng/μg protein or <1 EU/μg protein)

Recombinant proteins were run in SDS-PAGE under either DTT-reducing or non-reducing conditions, as indicated, to confirm purity of the recombinant protein was >95%.

Recombinant proteins run on an LC-Agilent 6230 Time-of-Flight Mass Spectrometer. Deconvoluted mass spectrums shown with predicted and observed molecular weights indicated.

Each lot of our bioassay-validated recombinant proteins undergoes quality testing by functional assay to ensure the protein exhibits appropriate activity within a biologically relevant system. In this way, we ensure our proteins will perform within your experimental system. Some applications we test our proteins for include:

  • Activation
  • Binding
  • Chemotaxis
  • Cytokine Production
  • Cytotoxicity
  • Differentiation
  • Expansion
  • Growth
  • In vivo Assays
  • Inhibition
  • Polarization
  • Proliferation
  • Signaling
  • Standard Cell Culture
  • And many more...

Inhibition Assay


Recombinant Human TGF-β1

Proliferation of HT-2 cells induced by mouse IL-4 is inhibited by human TGF-β1.

We offer the majority of our recombinant proteins in a convenient, ready-to-use liquid format, which have a comparable shelf-life to lyophilized proteins.


Advantages of Liquid Recombinant Proteins:


  • Ready-to-use
  • No buffer preparation
  • No pH adjustment
  • No filtration
  • Reduced chance for contamination
  • No risk of protein aggregation during reconstitution


We perform extensive stability testing to ensure that each of our proteins is stable in a liquid format when handled and stored properly. In most cases, our liquid format recombinant proteins exhibit superior in-use shelf life when compared with competitor lyophilized proteins. If extended storage is desired, our proteins typically possess comparable long-term stability to competitors when stored at -80°C.


BioLegend (Liquid)

Competitor A (After Reconstitution)

Competitor B (After Reconstitution)


12 months

3 - 12 months

3 months


6 months

3 - 12 months

3 months


1-3 months

1 week

1 month

Stability Testing

Each recombinant protein released undergoes extensive stability testing to ensure product performance over the reagent’s entire shelf life.

Recombinant proteins were aliquoted in PBS pH 7.2 at 0.2 mg/ml. One aliquot was frozen and thawed four times (4x freeze/thaws), one was kept at RT, and one was kept at 37°C for one week. All samples were tested for bioactivity as compared to a control stored at 4°C.

Long-Term Stability Testing

We periodically retest our recombinant proteins at later time points and have shown that some recombinant proteins retain their activity even after 10 years in storage at -80°C.

Recombinant proteins stored at -80°C for 10 years were tested for bioactivity as compared to a fresh competitor  lyophilized protein.

Product Authors Journal Year Vol/Page Pubmed
Recombinant Mouse CCL3 (MIP-1α) (carrier-free) Popova T, et al. PLoS One 2016 11: 0163163 Link
Recombinant Human CD40L (TNFSF5) (carrier-free) Sayin I, et al. J Exp Med 2018 7:40286 Link
Recombinant Mouse CX3CL1 (Fractalkine) (carrier-free) Dorfman M, et al. Nat Commun 2017 8:14556 Link
Recombinant Mouse CXCL1 (KC) (carrier-free) Kamp M, et al. PLoS One 2016 11: 0163750 Link
Recombinant Human CXCL10 (IP-10) (ELISA Std.) Ramirez L, et al. J Leukoc Biol 2014 96:1055 Link
Recombinant Mouse CXCL10 (IP-10) (carrier-free) Pfeiffer A J Gen Virol 2015 96:1328 Link
Recombinant Human CXCL10 (IP-10) (carrier-free) Sek A, et al. PLoS One 2015 10: 0133266 Link
Recombinant Human CXCL10 (IP-10) (carrier-free) Li Y, Kaneda T Sci Rep 2016 6: 25077 Link
Recombinant Human EGF (carrier-free) Tam A, et al. Sci Rep 2019 9:3353 Link
Recombinant Mouse EGF (carrier-free) Pei G, et al. Mol Biol Cell 2015 26: 3061-3070 Link
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