FLT3 is a receptor tyrosine kinase of 130-155 kDa expresssed on normal
bone marrow stem and early progenitor cells and on leukemic blasts fr
om patients with acute leukemias. The FLT3 ligand, FL, is a new cytoki
ne which acts on hematopoietic progenitors in synergy with other cytok
ines. FLT3 transduces FL-mediated signal through interaction with a nu
mber of cytoplasmic substrates.