Recombinant human IFN alpha 2B (HZ-1072) dose-dependently inhibits growth of the TF-1 cell line. Cell number was quantitatively assessed by PrestoBlue® Cell Viability Reagent. TF-1 cells were treated with increasing concentrations of recombinant IFN alpha 2B for 72 hours. The EC50 was determined using a 4-parameter non-linear regression model. The EC50 range is 0.004-0.020 ng/mL.