The Promyelocytic Leukemia (PML) gene was originally identified at the breakpoint of the t(15;17) translocation of Acute Promyelocytic Leukemia (APL), which generates the PML/retinoic acid receptor (RAR)α oncogene, an inhibitor of PML and RARα functions (Salomoni et al., 2008) [please refer to accompanying articles1 and reviews in the field, e.g. (Grimwade and Solomon, 1997; Brown et al., 2009; de The and Chen, 2010), for detailed information on APL pathogenesis]. Here, RARA is linked to leukemia.