FLT3 is a member of the class III receptor tyrosine kinase family and its internal tandem duplication (ITD) is preferentially seen in acute myeloid leukemia and myelodysplastic syndrome among various hematological malignancies. It is a membrane bound glycosylated protein that is expressed primarily in early hematopoietic progenitor cells. Upon binding its ligand FL, FLT3 activates multiple signaling pathways including the PI3K/Akt and Ras/MEK/MAPK pathways. In cells expressing FLT3-ITD, these pathways are constitutively on, resulting in abnormal cell growth and anti-apoptotic activity.Synonyms: FL cytokine receptor, STK1, Stem cell tyrosine kinase 1, Tyrosine-protein kinase receptor FLT3