FLT3, also known as Cluster of differentiation antigen 135 (CD135), is a member of the tyrosine kinase receptor family. FLT3 is a cytokine receptor which belongs to the receptor tyrosine kinase class III. CD135 is the receptor for the cytokine Flt3 ligand (FLT3L). It is expressed on the surface of many hematopoietic progenitor cells. Signaling through FLT3 plays a role in cell survival, proliferation, and differentiation.