Technote | LIF (Qk036)

Higly bioactive, animal-free leukemia inhibitory factor


Leukemia Inhibitory Factor (LIF) belongs to the IL-6 cytokine family and regulates embryonic development, immune response, and inflammation. LIF is essential to maintain stem cell pluripotency, so it is widely used in embryonic and induced pluripotent stem cell cultures. Leukemia inhibitory factor can also differentiate and maintain immune cells, such as T cells and macrophages.

Animal-free growth factors can ensure that cell cultures are reproducible and physiologically relevant as they have higher lot-to-lot consistency and eliminate contamination from animal-derived ingredients. Qkine manufactures an animal-free, carrier-free, and tag-free LIF to ensure high and consistent bioactivity. This technote demonstrates a comparable level of bioactivity between Qkine leukemia inhibitory factor and an alternative major supplier of bacterial-expressed LIF (Supplier B).


The bioactivity of Qk036 LIF and Supplier B LIF from an alternative supplier is determined using the LIF-responsive firefly luciferase reporter assay. HEK293T cells are treated in triplicate with a serial dilution of LIF overnight. Firefly luciferase activity is measured and normalized to the control Renilla luciferase activity.


The bioactivity comparison demonstrates that Qk071 LIF has equivalent bioactivity to leukemia inhibitory factor from an alternative major supplier. Qkine LIF provides a reliable source of highly pure animal-free LIF for the reproducible culture of stem cells and immune cells.

Qkine LIF and all Qkine recombinant proteins come with a Bioactivity Guarantee, guaranteeing our proteins to be reproducibly bioactive in your cultures.

Qkine human LIF bioactivity_competitor comparison

Quantitative luciferase reporter assay shows that both LIF (Qk036, green) and alternative supplier LIF (Supplier B, black) have high bioactivity with an EC50 of 0.28 ng/ml (16 pM) and 0.29 ng/ml (17 pM), respectively. Data for Qk03 lot #104293.

All our recombinant proteins are animal-free
& come with Bioactivity. Guaranteed.

Featured resources


Organoid brochure

Human iPSC directed
differentiation poster


Qkine recombinant LIF protein technote

Highly bioactive, animal-free LIF technote


Lifetime - engineering underpinning medicine PhD studentship sponsored by Qkine

Designing biomimetic neural materials for 3D cell culture

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Our dedicated team of stem cell specialists is available to answer any queries and to give expert support when required.

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Our dedicated team of stem cell specialists is available to answer any queries and to give expert support when required.