Recombinant GM-CSF is a bioactive protein intended for use in cell culture applications. Recombinant human GM-CSF is intended for use in cell culture applications. GM-CSF is involved in many biological responses including the growth and development of granulocyte and macrophage progenitor cells, stimulation and the initiation of differentiation of myeloblasts and monoblasts, and chemotaxis of eosinophils. ED50 range = 0.02 to 0.1 ng⁄mL, determined by the dose dependent proliferation of human TF-1 cells. Optimal concentration for individual application should be determined by a dose response assay.