Flt3l (FMS-like tyrosine kinase 3 ligand) is a cytokine and a hematopoietic growth factor. It acts as a ligand for FLT3 receptor. Alternative splicing of FLT3L results in both membrane-bound and soluble forms. Soluble form is a result of proteolytic cleavage of the membrane isoform. It has a wide range of tissue expression.

Mouse and human Flt-3 ligand share approximately 72% homology and both demonstrate cross-species activity.

Flt3l (FMS-like tyrosine kinase 3 ligand) acts as a stimulant of hematopoietic progenitor cell proliferation. It facilitates the commitment of lymphoid lineage, and aids in dendritic cell (DC) development. It is involved in myeloblast differentiation, and drives skeletal muscle regeneration. It acts on p120RasGAP and suppresses Erk signaling, which in turn promotes myogenesis. In lymphoid tissues, it modulates DC homeostasis, which is facilitated by steady state as well as proliferative T-cells.

Heterogenous glycosylation causes recombinant mouse Flt-3 ligand to migrate as multiple bands from 18-32 kDa.

Lyophilized from a 0.2 μm filtered solution in 50% acetonitrile and 0.1% trifluoroacetic acid containing 50 μg bovine serum albumin per 1 μg of cytokine.

Bioactivity is measured by the ability to stimulate the proliferation of a Flt-3 transfected pro-B cell line.