To investigate further the metabolic changes occurring in APL blasts and to define the role of PML::RARα in these events, we used the PR9 cells (U937 cells carrying the PML::RARα cDNA under a ZnSO4-inducible promoter) and control (MT) cells (U937 cells bearing an empty vector). This evidence concerns the gene RARA and acute promyelocytic leukemia.