Recombinant bovine/porcine FGF2-G3 154 aa protein (Qk081)

Recombinant bovine/porcine FGF2-G3 protein is a thermostable engineered form of FGF-2 (bFGF). Qk081 is the 154 aa mature domain of FGF-2 (Qk056). FGF2-G3 has an increased functional half-life from <10 h (wild-type) to >7 days (FGF2-G3). Bovine FGF2-G3 is used for the development of optimized serum-free culture media for species-specific bovine (cow) cultivated meat and veterinary research applications including the expansion of bovine smooth muscles cells, bovine induced pluripotent, embryonic and mesenchymal stem cells.

Recombinant FGF2-G3 is used in B8 media (Kuo et al. 2019) and Beefy-9 media (Stout et al. 2023) for weekend free, high homogeneity induced pluripotent stem cell culture. FGF2-G3 also has applications in chemically defined stem cell and organoid culture media.

Bovine FGF2-G3 has a molecular weight of 17.2 kDa. This protein is carrier-free and tag-free to ensure its purity with exceptional lot-to-lot consistency.

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  • High purity thermostable bovine/porcine FGF2-G3

  • >98%, by SDS-PAGE quantitative densitometry

  • Source: Expressed in E. coli 

  • 17.2 kDa (Monomer)

  • Animal-free (AOF) and carrier protein-free

  • Manufactured in Cambridge, UK

  • Lyophilized from Tris/NaCl/CyS/mannitol

  • Resuspend in water at >100 µg/mL, prepare single-use aliquots, add carrier protein if desired, and store frozen at -20oC or -80oC

Featured applications

  • Expansion of bovine and porcine induced pluripotent, embryonic and mesenchymal stem cells

  • Cell expansion

  • Proliferation of fibroblasts and endothelial cells

  • Tissue repair and regeneration

  • Cell growth and proliferation of bovine and porcine smooth muscle cells

Basic fibroblast growth factor
Fibroblast growth factor-basic



Bioactivity graph showing the EC50 of 415 pg/ml (24 pM) for Qkine recombinant bovine/porcine FGF2-G3 154 aa

Recombinant bovine/porcine FGF2-G3 activity is determined using the Promega serum response element luciferase reporter assay (*) in transfected HEK293T cells. EC50 = 415 pg/ml (24 pM).

Cells are treated in triplicate with a serial dilution of FGF2-G3 for 3 hours. Firefly luciferase activity is measured and normalized to the control Renilla luciferase activity. Data from Qk081 lot #204612.

*Promega pGL4.33[luc2P/SRE/Hygro] #E1340


SDS-PAGE gel showing the high purity reduced and non-reduced forms of bovine/porcine FGF2-G3 154 aa

Recombinant bovine/porcine FGF2-G3 154aa migrates as a major band at approximately 17 kDa (monomer) in reduced (R) and non-reduced (NR) conditions. The dimeric form is also observed at approximately 34 kDa in the non-reduced condition. No contaminating protein bands are present.

The purified recombinant protein (7 µg) was resolved using 15% w/v SDS-PAGE in reduced (+β-mercaptoethanol, R) and non-reduced (NR) conditions and stained with Coomassie Brilliant Blue R250. Data from Qk081 lot #204612.

Further quality assays

  • Mass spectrometry, single species with the expected mass

  • Endotoxin: <0.005 EU/μg protein (below the level of detection)

  • Recovery from stock vial: >95%

We are a company founded and run by scientists to provide a service and support innovation in stem cell biology and regenerative medicine.  All our products are exceptionally high purity, with complete characterisation and bioactivity analysis on every lot.

Wild-type bovine/porcine FGF-2 and bovine/porcine FGF2-G3 have equivalent bioactivity


Bovine/porcine FGF2-G3 activity is determined using the Promega serum response element luciferase reporter assay (*) in transfected HEK293T cells. Cells are treated in triplicate with a serial dilution of FGF2-G3 for 3 hours.

Qk081 bovine/porcine FGF2-G3 (EC50 0.209 ng/ml) and Qk056 WT FGF-2  (EC50 0.236 ng/ml)

*Promega pGL4.33[luc2P/SRE/Hygro] #E1340

Compared to wild-type bovine/porcine FGF-2, thermostable bovine/porcine FGF2-G3 retains activity after pre-incubation with conditioned media at 37°C for 48 hours

Wild-type FGF-2


0 hours    + 48 hours

WT FGF-2 (Qk056) and FGF2-G3 (Qk081) were diluted in conditioned media and incubated at 37 °C. Samples were taken at 0 and 48 hours. FGF-2 activity was assayed in triplicate using the Promega serum response element luciferase reporter assay (*) in transfected HEK293T cells.  Results were then normalized to the maximum response for 0 hours. 

Comparison between Qk056 WT FGF-2 at 0 hours (EC50 0.105 ng/ml) and 48 hours (EC50 could not be fitted)

Comparison between Qk081 FGF2-G3 at 0 hours (EC50 0.128 ng/ml) and 48 hours (EC50 0.103 ng/ml) 

Protein background

FGF-2 (also known as basic FGF or bFGF) is an essential growth factor for maintaining embryonic stem cell (ESC) and induced pluripotency stem cell (iPSC) pluripotency in feeder-free and chemically defined stem cell media. It is a core component of widely adopted media including mTESR [1], StemPRO [2] and E8 [3]. However, FGF-2 is inherently unstable and prone to proteolytic degradation and aggregation. This fundamental biochemical instability, and therefore low half-life in culture media (<10 h), is an important contribution to the need for frequent media changes and challenges in improving homogeneity during stem cell proliferation and subsequent differentiation.

Bovine/porcine FGF2-G3 can be a core ingredient in Beefy-9 media, established by Stout et al. in 2023. The innovation of adding recombinant albumin to B8 media has yielded a groundbreaking advancement in cell culture for the growth of bovine satellite cells, resulting in the development of Beefy-9 media. This novel medium is the first of its kind, meeting fundamental criteria to serve as a foundational medium for cultured meat production. One key feature includes the complete absence of animal-derived components, ensuring animal-component-free culture conditions. This departure from traditional serum-containing media, which often rely on animal-derived additives, distinguishes Beefy-9’s commitment to ethical and sustainable practices in cell culture [4-6].

  1. Ludwig, Tenneille E., et al. ‘Feeder-Independent Culture of Human Embryonic Stem Cells’. Nature Methods, vol. 3, no. 8, Aug. 2006, pp. 637–46.
  2. Wang, Linlin, et al. ‘Self-Renewal of Human Embryonic Stem Cells Requires Insulin-like Growth Factor-1 Receptor and ERBB2 Receptor Signaling’. Blood, vol. 110, no. 12, Dec. 2007, pp. 4111–19.
  3. Beers, Jeanette, et al. ‘Passaging and Colony Expansion of Human Pluripotent Stem Cells by Enzyme-Free Dissociation in Chemically Defined Culture Conditions’. Nature Protocols, vol. 7, no. 11, 2012, pp. 2029–40.
  4. Stout, A. J. et al. A Beefy-R culture medium: Replacing albumin with rapeseed protein isolates. Biomaterials 296, 122092 (2023).
  5. Kuo, H. H. et al. Negligible-Cost and Weekend-Free Chemically Defined Human iPSC Culture. Stem Cell Reports 14, 256–270 (2020).
  6. Mcaleer, C. W., Rumsey, J. W., Stancescu, M. & Hickman, J. J. Functional myotube formation from adult rat satellite cells in a defined serum-free system. Biotechnol. Prog. 31, 997–1003 (2015).

Our products are for research use only and not for diagnostic or therapeutic use.  Products are not for resale.

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