PML and acute promyelocytic leukemia: ATRA targets the RARα part of the fusion, while ATO targets the PML part,17,18 which promotes the degradation of PML/RARα and then affects the expression of its downstream target genes, such as WT1, C/EBPbeta, and GATA2. 19,20,21 These genes are important for APL cell differentiation or proliferation.