CD135 is a tyrosine kinase receptor expressed on normal cells including CD34+ hematopoietic stem cells, myelomonocytic progenitors, primitive B cell progenitors, and thymocytes. CD135 is also expressed on malignant hematopoietic cells including AML, ALL and CML BC. CD135, also known as FMS-like tyrosine kinase 3, FLT3, STK1, and Flk2, is a growth factor receptor that binds the FLT3 ligand to promote the growth and differentiation of primitive hematopoietic cells. The intracytoplasmic domain