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PML is the organizer of PML Nuclear Bodies (NBs) and recruits onto these sub-nuclear structures a striking variety of very diverse proteins, several of which are implicated in apoptosis.PML may be conjugated bythe small-ubiquitin-like proteins SUMO-1/2/3 and PML conjugation is required for the recruitment of the other NB-associated proteins.SUMO targets 3 specific lysine residues: K65 within the RING finger, K490 within the nuclear localization signal and K160 in the B box.Conjugation of K 160 is greatly enhanced by As2O3, controls recruitment of partner proteins, including the 11S proteasome complex, and is required for As2O3-induced PML degradation.Here, we show that SUMO-1, but not SUMO2, triggers the nuclear import of PML.In addition, PML colocalised with SUMO-1 only in the nucleus, while SUMO-2 colocalisation was also observed in the cytoplasm.While, K160 was preferentially modified by SUMO-2, the K490 site only enabled colocalization with SUMO-1.FRET experiments show that As2O3 predominantly induces SUMO-2 modification of PML.PML sumolation is induced in S phase, but abrogated in M and, accordingly, As2O3-induced PML sumolation was impeded in mitosis.Thus, differential modifications bySUMO-1 and SUMO-2/3 of the PML sumolation sites K490 and K160 modulate properties of PML, including its nucleo/cytoplasmic localisation.