Engineering novel functionality or specificity into growth factor proteins is a research time and resource intensive process.  Successful new engineered proteins with unique properties of interest to stem cell science or regenerative medicine shouldn’t be retired to the back of the freezer.

To support translational of basic science, we are proud to launch our Pioneering Protein range; modified proteins developed by academic laboratories and manufactured to our high purity and bioactivity standards.

  • protein alterations developed by world-leading groups
  • licensed through technology transfer process
  • highest quality animal-free manufacture
  • stringent purity and bioactivity testing
  • adding value and innovation to stem cell science

interested in adding your own protein to the range? contact


follistatin-resistant activin A, FRACTA (Qk035)

follistatin inhibits Activin A

Activin A is regulated by negative feedback due to accumulation of follistatin

removing inhibition by follistatin

Follistatin Activin A is not inhibited by accumulation of follistatin

bioactivity is maintained

Wild type and follistatin resistant Activin have equivalent bioactivity

Activin A protein activity is determined using an activin-responsive firefly luciferase reporter in HEK293T cells.  EC50 for wild-type activin A (Qk001) = 8.776 pM, EC50 for follistatin-resistant activin A (FRACTA, Qk035) =8.792 pM.

Activin A, used widely in iPSC culture, is inhibited by follistatin; consequently activin A activity fluctuates in stem cell cultures.  Each passage with fresh activin A containing media leads to high activin A activity, which declines as follistatin accumulates.

Follistatin-resistant Activin A (FRACTA) has the same bioactivity as wild-type activin A (Qk001) but is not affected by the natural feedback inhibition by follistatin.

This specialized activin A was developed in Dr Marko Hyvönen’s lab (University of Cambridge).

learn more about FRACTA

High affinity LGR5 receptor-binding R-spondin 1 LR5 (Qk031)

R-spondin 1 LR5 specifically activates Wnt signalling in lgr5+ stem cell population

Organoid survival is maintained

Organoid survival

Crypt multiplicity is reduced

Intestinal organoid crypt multiplicity

All organoid data from the laboratory of Marc de la Roche and reproduced with permission (© Marc de la Roche, 2020).

R-spondin 1 LR5 protein (Qk031) is a specialized form of R-spondin 1 that specifically binds to the LGR5 receptor, developed in the lab of Marc de la Roche (University of Cambridge).

R-spondin 1 (Qk006) is a ligand for the leucine-rich repeat-containing G-protein coupled receptors (LGR) 4-6. Binding of R-spondin 1 to its coreceptors, LGR4-6 and ZNRF3, releases the inhibition ZNRF3 imposes on wnt signalling.

In epithelial tissues LGR5 marks the stem cell population. This engineered form, R-spondin1 LR5, activates wnt signalling only in the LGR5+
stem cell population.

R-spondin1 LR5 support organoid survival and growth in intestinal organoid culture.   As LGR5 specifically marks stem cells and is not found on transit amplifying cells, lower crypt multiplicity is seen in organoid cultures with R-spondin1 LR5 (in comparison with WT R-spondin1), which supports the notion that this engineered form is acting specifically on stem cells.

learn more about R-spondin 1 LR5

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