Purity of recombinant human LIF was determined by SDS- polyacrylamide gel electrophoresis. The protein was resolved in an SDS- polyacrylamide gel in reducing and non-reducing conditions and stained using Coomassie blue.
Recombinant human LIF (HZ-1292) dose-dependently inhibits growth of the M1 cell line. Cell number was quantitatively assessed by PrestoBlue® Cell Viability Reagent. M1 cells were treated with increasing concentrations of recombinant LIF for 96 hours. The EC50 was determined using a 4-parameter non-linear regression model. The EC50 range is 0.045-0.25 ng/mL.

The activity was determined by the dose-dependent stimulation of the proliferation of human TF-1 cells (human erythroleukemic indicator cell line) using Promega CellTiter96® Aqueous Non-Radioactive Cell Proliferation Assay.