Technote | FGF-8b (Qk057)

Fibroblast growth factor 8b protein has exceptional lot-to-lot consistency 


Fibroblast growth factor 8b (FGF-8b) is a spliced form of FGF8, a member of the FGF family. FGF-8b is involved in the regulation of embryogenesis and is commonly used for the differentiation of induced pluripotent stem cells into neural cell types and for brain organoid cultures. It is crucial to have reliable growth factors to ensure the neural cultures are reproducible and physiologically relevant. Growth factors developed in an animal-free expression system have fewer risks of batch-to-batch variability and contamination from animal-derived ingredients. Qkine developed a carrier-free, tag-free, and non-glycosylated FGF-8b expressed in E. coli to ensure the bioactivity is consistent.


The bioactivity of different lots of FGF-8b was determined using the Promega serum response element luciferase reporter assay in HEK293T cells. Cells were treated in triplicate with a serial dilution of FGF-8b for 3 hours. Firefly luciferase activity was measured and normalized to the control Renilla luciferase activity.  


The bioactivity comparison between different lots of FGF-8b protein expressed in E. coli showed they both have a similar EC50 value. The exceptional lot-to-lot consistency of FGF-8b provides a reliable source of animal-free FGF-8b for the reproducible culture of neural stem cells and other FGF-8b-dependent applications. 

Qk057 FGF-8b lot-to-lot consistency comparison

Quantitative luciferase reporter assay shows that both batches of FGF-8b have a consistent EC50 of 2.2 ng/mL and 2.9 ng/mL, respectively (0.1 pM and 0.13 pM). Data from Qk057 lot #104442 and #104467. 

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