ENDOTOXIN LEVEL <0.1 EU per 1 μg of the protein by the LAL method. Human Recombinant GMP Grade SCF. Stem Cell Factor (SCF) is a stromal cell-derived cytokine synthesized by fibroblasts and other cell types. SCF promotes proliferation and early differentiation of cells at the level of multipotential stem cells. SCF is a growth factor important for proliferation, and differentiation of hematopoietic stem cells. One of its roles is to change the BFU-E (burst-forming unit-erythroid) cells, which are the earliest erythrocyte precursors in the erythrocytic series, into the CFU-E (colony-forming unit-erythroid).