Cancer-exome-sequencing endeavours have recently revealed that core components of the KDM2B/PRC1 complex, including KDM2B itself and BCOR/L1, are frequently mutated in a range of cancers, particularly leukemias (Brookes et al., 2012; Grossmann et al., 2011; Pasqualucci et al., 2011; Zhang et al., 2012). The gene discussed is KDM2B; the disease is leukemia.