PML NBs (promyelocytic leukaemia nuclear bodies) is subnuclear structure in mammalian cells, which widely takes part in kinds of biological events such as transcriptional regulation, genome stability, response to viral infection, apoptosis and tumor suppression. As protein post-translational modification, SUMO located in nucleus plays important roles in PML NBs formation and degradation. Recent research suggests that the human E3 ubiquitin ligase-RNF4(RING finger protein 4), mediates PML NBs degradation depending on SUMO-2/3 modification of PML, ATO(arsenic trioxide) could facilitate in this process. FRET(fluorescence resonance energy transfer)technology could be used in studying the protein-protein interaction of PML NBs and SUMO protein in living cells. Thus, it is far-reaching and significant to research deeply in the mechanism of the formation and degradation of PML NBs and the interaction between the important proteins during this pathway.