GMP Recombinant human FGF-8b (HZ-1103-GMP) stimulates dose-dependent proliferation of the NIH/3T3 mouse fibroblast cell line. Viable cell number was quantitatively assessed by Prestoblue Cell Viability Reagent. NIH/3T3 cells were serum starved in 0.02% FBS with 1 ug/mL heparin during treatment with increasing concentrations of recombinant human FGF-8b for 72hrs. Activity determination was conducted in triplicate on a validated bioassay. The EC50 was determined using a 4- parameter non-linear regression model. The EC50 values range from 10-60 ng/mL.