FLT3 and leukemia: Some therapeutically-targetable leukemia antigens originate from oncogenesis itself and are leukemia cell-specific, such as the BCR/ABL1 fusion protein in CML and Philadelphia (Ph)+ ALL, PML/RAR-α in acute promyelocytic leukemia, FLT3-ITD and mutated NPM1 in AML and IDH1/2.