FLT3 (fms like tyrosine kinase 3,Cluster of differentiation antigen 135 (CD135) ,fetal liver kinase-2 (Flk2)) is a protein that is a cytokine receptor which belongs to the receptor tyrosine kinase class III. FLT3 is the receptor for the cytokine Flt3 ligand (FLT3L). It is expressed on the surface of many hematopoietic progenitor cells. Signalling of FLT3 is important for the normal development of haematopoietic stem cells and progenitor cells. Signaling through FLT3 plays a role in cell survival, proliferation, and differentiation.