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Recombinant human / mouse FGF-8a protein (Qk059)

Fibroblast growth factor 8a (FGF-8a) is a member of the FGF family and plays a key role in the regulation of embryogenesis, cellular proliferation, differentiation, and migration. FGF8a is often used for the differentiation of induced pluripotent stem cells, embryonic stem cells, and neural stem cells.

FGF8a is a spliced form of FGF8, a heparin-binding protein that targets mammary and non-mammary cells expressing the FGF receptors. A 21.3kDa highly pure, bioactive recombinant protein produced in an animal-free expression system. This protein is
animal-origin free (AOF), carrier protein-free, tag-free, and non-glycosylated to ensure a pure homogenous protein with exceptional lot-to-lot consistency. Qk059 is suitable for enhanced reproducibility and physiologically relevant cultures.

Orders are typically shipped same or next day (except Friday).
Easy world-wide ordering, direct or through our distributors.

1000µg will be despatched as 2 x 500µg

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  • High purity human FGF-8a protein (Uniprot: P55075-2)

  • >98%, by SDS-PAGE quantitative densitometry

  • 21.3 kDa
  • Expressed in E. coli
  • Animal-origin free (AOF) and carrier protein-free

  • Manufactured in our Cambridge, UK laboratories
  • Lyophilized from HEPES/NaCl/mannitol

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

Featured applications

  • Neurite outgrowth from spiral ganglion neurons
  • Differentiation of ESCs and iPSCs into dopaminergic (DA) neurons
  • Morphogenesis of mid-hindbrain
  • Neuronal induction in neural development

AIGF, AIGFKAL6, Androgen-induced growth factor, FGF8, FGF-8, Fibroblast Growth Factor – 8, HBGF-8, Heparin Binding Growth Factor – 8, MGC149376

1. Belov AA and Mohammadi M: Molecular mechanisms of fibroblast growth factor signaling in physiology and pathology. Cold Spring Harb Perspect Biol. 5:5 (2013).

2. Liu R, Huang S, Lei Y, Zhang T, Wang K, Liu B, Nice EC, Xiang R, Xie K, Li J, et al: FGF8 promotes colorectal cancer growth and metastasis by activating YAP1. Oncotarget. 6:935–952 (2015).

3. Katoh M and Katoh M: Comparative genomics on FGF8, FGF17, and FGF18 orthologs. Int J Mol Med. 16:493–496 (2005).

4. Gemel J, Gorry M, Ehrlich GD and MacArthur CA: Structure and sequence of human FGF8. Genomics. 35:253–257 (1996).

5. Reuss, Bernhard, and Oliver von Bohlen und Halbach. “Fibroblast growth factors and their receptors in the central nervous system.” Cell and tissue research. 313(2): 139-57 (2003).

6. Sternberg PW and Alberola-Ila J: Conspiracy theory: RAS and RAF do not act alone. Cell. 95:447–450 (1998).

7. Thisse B, Thisse C. Functions and regulations of fibroblast growth factor signaling during embryonic development Dev Biol. 287(2):390-402 (2005).

8. Turner N and Grose R: Fibroblast growth factor signalling: From development to cancer. Nat Rev Cancer. 10:116–129 (2010).

9. Jaskoll T, Witcher D, Toreno L, Bringas P, Moon AM and Melnick M: FGF8 dose-dependent regulation of embryonic submandibular salivary gland morphogenesis. Dev Biol. 268:457–469 (2004).

10. Olsen SK, Li JY, Bromleigh C, Eliseenkova AV, Ibrahimi OA, Lao Z, Zhang F, Linhardt RJ, Joyner AL and Mohammadi M: Structural basis by which alternative splicing modulates the organizer activity of FGF8 in the brain. Genes Dev. 20:185–198 (2006).

11. Crossley PH, Minowada G, MacArthur CA, Martin GR. Roles for FGF8 in the induction, initiation, and maintenance of chick limb development. Cell. 84(1):127-136 (1996).

12. Heikinheimo M, Lawshé A, Shackleford GM, Wilson DB, MacArthur CA. Fgf-8 expression in the post-gastrulation mouse suggests roles in the development of the face, limbs and central nervous system. Mech Dev. 48(2):129-138 (1994).

13. Leerberg DM, Hopton RE, Draper BW. Fibroblast Growth Factor Receptors Function Redundantly During Zebrafish Embryonic Development. Genetics. 212(4):1301-1319 (2019).

14. Cooper O, Hargus G, Deleidi M, et al. Differentiation of human ES and Parkinson’s disease iPS cells into ventral midbrain dopaminergic neurons requires a high activity form of SHH, FGF8a and specific regionalization by retinoic acid. Mol Cell Neurosci. 45(3):258-266 (2010).

15. García-Hernández S, Potashner SJ, Morest DK. Role of fibroblast growth factor 8 in neurite outgrowth from spiral ganglion neurons in vitro. Brain Res. 1529:39-45 (2013).

16. Hulstrand AM, Houston DW. Regulation of neurogenesis by Fgf8a requires Cdc42 signaling and a novel Cdc42 effector protein. Dev Biol. 382(2):385-399 (2013).

17. Payson RA, Wu J, Liu Y, Chiu IM. The human FGF-8 gene localizes on chromosome 10q24 and is subjected to induction by androgen in breast cancer cells. Oncogene.13(1):47-53 (1996).

18. Ghosh AK, Shankar DB, Shackleford GM, et al. Molecular cloning and characterization of human FGF8 alternative messenger RNA forms. Cell Growth Differ. 7(10):1425-1434 (1996).

19. Nezu M, Tomonaga T, Sakai C, et al. Expression of the fetal-oncogenic fibroblast growth factor-8/17/18 subfamily in human hematopoietic tumors. Biochem Biophys Res Commun. 335(3):843-849 (2005).

Human and Mouse


Bioactivity graph showing the EC50 of 110 ng/ml (5.2 nM) for Qkine recombinant human FGF-8a

FGF-8a activity is determined using the Promega serum response element luciferase reporter assay (*) in HEK293T cells. EC50 = 110 ng/ml (5.2 nM).

Cells are treated in triplicate with a serial dilution of FGF-8a in the presence of 10 µg/ml heparin for 3 hours. Firefly luciferase activity is measured and normalized to the control Renilla luciferase activity. Data from Qk059 lot #104406.

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


FGF-8a (Qk059) migrates as a single band at 21.3 kDa in non-reducing (NR) conditions and upon reduction (R).

Purified recombinant protein (3 µg) was resolved using 15% w/v SDS-PAGE in reduced (+β-mercaptothanol, R) and non-reduced (NR) conditions and stained with Coomassie Brilliant Blue R250. Data from Qk059 batch #104412.

Further quality assays

  • Mass spectrometry, single species with expected mass
  • Endotoxin: <0.005 EU/μg protein (below 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.

Protein background

FGF-8a is a heparin-binding protein and an isoform of FGF-8 belonging to a family of fibroblast growth factors (FGF) [1]. It was originally discovered as an essential growth factor for the androgen-dependent growth of mouse mammary carcinoma cells [2]. In mouse, there are eight spliced protein isoforms of FGF8 (a-h) whereas, in humans, there are four alternate spliced protein isoforms namely FGF-8a, FGF-8b, FGF-8e, and FGF-8f. These four FGF8 isoforms (a, b, e and f) are highly conserved between humans and mice. Human and murine FGF-8a and FGF-8b show 100% homology [3] whereas there is a 98% identity with human and murine FGF8e and FGF8f [4]. Human FGF-8a, a monomeric protein has a molecular weight of 21.3kDa with 182 amino acid (aa) residues covering the signal sequence domain, N-terminal domain, FGF domain and proline-rich C terminal sequence [5]. Its three-dimensional structure is composed of two antiparallel beta-sheet and several alpha-helices. The protein contains a conserved heparin-binding domain that is essential for its biological activity. This domain binds to heparin sulfate proteoglycans on the cell surface and helps to localize FGF8a to its target cells.

FGF-8, including the spliced forms, functions by binding the FGF receptors (FGFR) to activate the Ras/MAPK signaling pathway, a key pathway that contributes to several cellular processes. In general, the FGF family is involved in broad cellular and biological processes including cell proliferation, differentiation, survival, and apoptosis [6-8].

Functionally, FGF-8a has been shown to play a major role during prenatal development. It is widely expressed during embryogenesis and is a key player in epithelial-mesenchymal transitions [9]. During gastrulation, it contributes to the organization and induction role and regulates the patterning of organs in the embryos. These organs include the brain, eye, ear, limb, and heart [10-12].

Although, FGF-8 isoforms work in a coordinated and concerted manner, findings have suggested that they also have distinct key roles. FGF-8a is required for morphogenesis and neurogenesis [13]. A study using transgenic mice showed FGF-8a expands the midbrain while FGF-8b showed a transformational activity by transforming the midbrain into the cerebellum [10].

Furthermore, FGF-8a has been used to generate embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs)-derived ventral midbrain dopaminergic (DA) neurons [14]. FGF-8a has also been shown to play a role in neuronal induction during neural development and neurite outgrowth from spiral ganglion neurons in vitro [15-16].

Whilst there is limited expression of FGF-8 and its isoforms in the normal adult, increasing studies have shown the presence of FGF-8 in adult tissues and cells including the reproductive tract, peripheral leukocytes, and hematopoietic cells [17-19]. Further functional studies are required to fully delineate the role of FGF-8 and its isoforms in the normal adult.

Additional resources

Technote: FGF-8a

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

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