FLT-3 Ligand is a growth factor that regulates proliferation of early hematopoietic cells. FLT-3 Ligand binds to cells expressing the tyrosine kinase receptor FLT-3. FLT-3 Ligand by itself does not stimulate proliferation of early hematopoietic cells, but synergizes with other CSFs and interleukins to induce growth and differentiation Unlike SCF, FLT-3 Ligand exerts no activity on mast cells. Multiple isoforms of FLT-3 Ligand have been identified The predominant biologically active form is anchored to the cell surface as the extracellular domain of a transmembrane protein (209 aa) The membrane-bound isoform can be proteolytically cleaved to generate a biologically active soluble isoformThe biological activity of CTGrade GMP interleukins and growth factors is standardized, where applicable, to WHO International standards, providing cell and gene therapy developers consistent, lot-to-lot biological activity and performance.