PML and acute promyelocytic leukemia: APL, a particular subtype of acute myeloid leukemia (AML) with a distinct cytologic morphology (M3 and M3 variant in French-American-British (FAB) classification), is characterized by a chromosome translocation t (15; 17), which results in the rearrangement of promyelocytic leukemia (PML) gene and retinoic acid receptor-α (RARα) gene, and then the expression of PML-RARα fusion protein [3].