Stemfactor™ B18R Recombinant Protein, Carrier-free

Catalog Size Price Quantity
03-0017 50 ug $579.00
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Product Overview

Reprogramming-qualified B18R Recombinant Protein, Carrier-free (#03-0017) is useful for cellular reprogramming and other applications requiring RNA-mediated gene delivery.  B18R protein is a Vaccinia virus-encoded receptor with specificity for mouse, human, rabbit, pig, rat and cow Type 1 interferons and has potent neutralizing capability acting as a decoy receptor for Type 1 interferons.

Previously only available as part of the mRNA Reprogramming Kit (#00-0071) or microRNA Booster Kit (#00-0073), Reprogramming-qualified B18R Recombinant Protein, Carrier-free is now available for individual purchase.

Product Specifications


Product Name

StemfactorTM B18R Recombinant Protein, Carrier-Free 

Catalog Number



50 ug in 100 uL 


0.5 mg/mL 


Insect cells infected with baculovirus containing amino acids His20 – Glu 351 of vaccinia virus B18R accession number D01019, with a His tag. 


B18R is supplied as a sterile liquid in 10 mM phosphate, 0.5 M NaCl with a pH of 7.5 


Greater than 98% by SDS-PAGE analysis 

Endotoxin Level

Less than 0.5 EU/mg of B18R as determined by the LAL method 

Biological Activity

Stemfactor B18R Recombinant Protein, Carrier-free bioactivity is demonstrated by the neutralization of IFN- alpha or IFN-beta effects in an assay of IL-12 production from CD40L-activated monocytes

The biological function is validated by down-regulation of gene expression by qRT-PCR of TLR3, IFIT1, and OASI in response to B18R treatment on human fibroblasts to levels equivalent to non-transfected cells.  

The efficiency of mRNA reprogramming is tested by performing mRNA reprogramming with OKSML on neonatal foreskin fibroblasts and demonstrating greater than 0.5% iPSC colony formation. 


Tested to be negative for Mycoplasma sp. by RT-PCR and negative for microbial contamination by sterility testing. 

Storage and Handling

Stemfactor B18R Recombinant Protein, Carrier-free is shipped on dry ice.  For long-term storage, aliquot and store at -80 degrees C. Avoid freeze-thaw cycles. 


Stable for up to 6 months from date of receipt when stored as directed. 

Manufactured by 



Warren L, Manos PD, Ahfedlt T, Loh YH, Li H, Lau F, Ebina W, Mandal PK, Smith ZD, Meissner A, Daley GQ, Brack AS, Collins JJ, Cowan C, Schlaeger TM, Rossi DJ. Highly efficient reprogramming to pluripotency and directed differentiation of human cells with synthetic modified mRNA. Cell Stem Cell, 7(5):618-30 (2010).

Specification Sheets

Safety Data Sheets

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