These findings further strengthen the hypothesis that inhibitors of Pml (e.g., arsenic trioxide/AS2O3, already in use for the treatment of promyelocytic leukemia) may be used for the treatment of CML, as well as in AML harboring the MLL–AF9 fusion protein or expressing high levels of HoxA9 and Meis1. This evidence concerns the gene MLLT3 and acute promyelocytic leukemia.