Stem cell factor lacks an independent proliferative effect yet is synergistic with TPO-induced proliferation in primary megakaryocyte-lineage cells.

TPO-responsive GPIIb-tva⁺mpl^−/−bone marrow cells expressing Mpl, MplY582F, and MplΔ50 were grown in the presence of 10 ng/mL SCF and 250 ng/mL h-TPO, 250 ng/mL h-TPO, 10 ng/mL SCF, or no added cytokine, and total cell counts were recorded on the days indicated. Each point represents the average of 3 independent experiments.