The proliferation of TF-1 cells treated with increasing concentrations of hLIF was assessed. After 72 hr treatment with hLIF, cells were incubated with a tetrazolium salt and the OD450 - OD650 was determined.
The purity of recombinant hLIF was determined by SDS-PAGE of 6 µg reduced (+) and non-reduced (-) recombinant hLIF and staining overnight with Coomassie Blue.
Western blot analysis of extracts from TF-1 cells untreated or treated with hLIF for 10 min, using Phospho-Stat3 (Tyr705) (D3A7) XP® Rabbit mAb #9145 (upper) or Stat3 Antibody #9132 (lower).
With carrier: Lyophilized from a 0.22 μm filtered solution of PBS, pH 7.2 containing 20 μg BSA per 1 μg hLIF. Carrier free: Lyophilized from a 0.22 μm filtered solution of PBS, pH 7.2.
Stable in lyophilized state at 4°C for 1 year after receipt. Sterile stock solutions reconstituted with carrier protein are stable at 4°C for 2 months and at -20°C for 6 months. Avoid repeated freeze-thaw cycles.Maintain sterility. Storage at -20°C should be in a manual defrost freezer.
>98% as determined by SDS-PAGE of 6 μg reduced (+) and non-reduced (-) recombinant hLIF. All lots are greater than 98% pure.
Based on amino acid sequencing, greater than 30% of recombinant hLIF has a Met on the amino-terminal Ser23 (MSPLP) and has a calculated MW of 19,847. The remainder starts at Ser23 (SPLPI), Pro24 (PLPIT), or Pro26 (PITPV). DTT-reduced protein migrates as a 20 kDa polypeptide and non-reduced protein migrates as a 17 kDa polypeptide due to intramolecular cystines.
The bioactivity of recombinant hLIF was determined in a TF-1 cell proliferation assay. The ED50 of each lot is between 0.2-1.5 ng/ml.
Less than 0.01 ng endotoxin/1 μg hLIF.
Recombinant human LIF (hLIF) Ser23-Phe202 (Accession #P15018) was produced in E. coli at Cell Signaling Technology.
Leukemia Inhibitory Factor (LIF) is a 20 kDa pleiotrophic factor belonging to the IL-6 superfamily of cytokines (1). LIF is expressed in a number of tissues and cell types. The LIF receptor is a heterodimer comprised of LIF-R (gp190) and gp130, a common signal transducer for IL-6-type cytokines (1). Depending on cell type and context, LIF/LIF-R can activate Erk, PI3K, and Jak1/Stat1/3 pathways (1,2). LIF has a diverse array of biological activities. Murine embryonic stem cells are dependent on LIF for pluripotency and self-renewal in vitro (1). Exercise- induced LIF secretion in muscle induces myoblast proliferation, suggesting that LIF may play a role in exercise-induced muscle hypertrophy (2). LIF also negatively regulates Th2 and Th17 cell differentiation (3,4).
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