Flt3-Ligand is a growth factor that regulates proliferation of early hematopoietic cells. Flt3-Ligand binds to cells expressing the tyrosine kinase receptor Flt3. Flt3-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, Flt3-Ligand has no activity on mast cells. Multiple isoforms of Flt3-Ligand have been identified. The predominant biologically active form is anchored to the cell surface as the extracellular domain of a transmembrane protein (209 a.a.). The membrane-bound isoform can be proteolytically cleaved to generate a biologically active soluble isoform. Recombinant mouse Flt3-Ligand is a soluble 18.6kD protein consisting of 163 amino acid residues. Amino Acid Sequence: MTPDCYFSHS PISSNFKVKF RELTDHLLKD YPVTVAVNLQ DEKHCKALWS LFLAQRWIEQ LKTVAGSKMQ TLLEDVNTEI HFVTSCTFQP LPECLRFVQT NISHLLKDTC TQLLALKPCI GKACQNFSRC LEVQCQPDSS TLLPPRSPIA LEATELPEPR PRQ Biological Activity: Determined by the dose-dependent stimulation of the proliferation of human AML5 cells. The expected ED50 for this effect is 5.0-8.0ng/ml. Storage and Stability: Lyophilized and reconstituted products are stable for 6 months after receipt at -20C. Reconstitute with sterile ddH2O, 0.1% HSA or BSA. Aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer.