Human Flt3 Ligand (Flt3L) Recombinant Protein, eBioscience?. Flt3 (FMS-related tyrosine kinase 3) Ligand is a growth factor that stimulates the growth and differentiation of early hematopoetic progenitor cells. Flt3 Ligand alone exerts weak biological effects, and instead synergizes with other colony-stimulating factors to induce the proliferation and differentiation of cells of the myeloid and lymphoid lineages. Recent studies have suggested that Flt3 Ligand plays an important role in the development and expansion of dendritic cells in vivo, and that it may influence NK cell survival by this mechanism.Flt3 Ligand transcripts are detectable in most cell types and tissues, although the protein has only been found in stromal cells and T