Activity of murine LIF was determined by the M1 cell differentiation assay which was found to be < 0.01 ng/mL, corresponding to a specific activity of 100,000,000 IU/mg.
A standard of 50 Units is defined as the concentration of mouse LIF in 1.0 mL of tissue culture medium that induces the differentiation of 50% of M1 colonies.
Storage Buffer:
Lyophilized from 20mM Phosphate buffer pH-7.4 and 0.02% Tween-20
Storage Instruction:
Lyophilized although stable at room temperature for 3 weeks, should be stored desiccated below -20°C. Upon reconstitution should be stored at 4°Cbetween 2-7 days and for future use below -20°C. For long term storage it is recommended to add a carrier protein (0.1% HSA or BSA). Aliquot to avoid repeated freezing and thawing.