“…The PML protein has first been described as the causal agent in acute promyelocytic leukaemia as a fusion with the RARa receptor generated by the chromosomal translocation t(15;17) (Ascoli and Maul, 1991;de The et al, 1991;Kakizuka et al, 1991;Chang et al, 1992;Goddard et al, 1992;Kastner et al, 1992;Pandolfi et al, 1992;Dyck et al, 1994;Koken et al, 1994;Weis et al, 1994;Melnick and Licht, 1999;. Since these initial findings, it has become evident that PML is a general tumour suppressor frequently deregulated in various tumour types (Gurrieri et al, 2004) most presumably involving secondary effects of PML bodies as sites of protein degradation (Lallemand-Breitenbach et al, 2001), transcriptional regulation (Li et al, 2000;Zhong et al, 2000), cellular senescence (Ferbeyre et al, 2000;Pearson et al, 2000;Bischof et al, 2002;Langley et al, 2002), tumour suppression (Salomoni and Pandolfi, 2002;Salomoni et al, 2008), DNA repair (Bischof et al, 2001;Carbone et al, 2002), apoptosis (Hofmann and Will, 2003;Takahashi et al, 2004) and epigenetic regulation (Torok et al, 2009). Interestingly, functional inactivation of the E1B-55K leucine-rich nuclear export sequence (NES) induces enhanced posttranslational modification of E1B-55K by the small ubiquitin-related modifier 1 (SUMO1) at lysine 104 (SUMO-conjugation motif, SCM) as well as augments transformation of primary rat cells involving the accumulation of p53, E1B-55K and PML in subnuclear aggregates (Endter et al, 2001(Endter et al, , 2005.…”