The role of TGFβ in leukemogenesis has been recently studied in acute promyelocytic leukemia (APL), a distinct subtype of acute myeloid leukemia (AML) associated with t(15;17) and expression of the promyelocytic leukemia-retinoic acid receptor alpha (PML-RARα) hybrid protein. Here, RARA is linked to acute promyelocytic leukemia.