PLZF-RAR alpha fusion proteins generated from the variant t(11;17)(q23;q21) translocation in acute promyelocytic leukemia inhibit ligand-dependent transactivation of wild-type retinoic acid receptors..     ///    "A ""dominant negative"" effect was observed when PLZF-RAR alpha fusion proteins were cotransfected with vectors expressing RAR alpha and retinoid X receptor alpha (RXR alpha). "    ///    These abnormal transactivation properties observed in retinoic acid-sensitive myeloid cells strongly implicate the PLZF-RAR alpha fusion proteins in the molecular pathogenesis of APL..     ///    We have now cloned cDNAs encoding PLZF-RAR alpha chimeric proteins and studied their transactivating activities. 