The transcript of the long form of the MDS1-EVI1/PRDM3 gene is expressed at very low levels in leukaemia cells, whereas the short form of the EVI1 gene is over-expressed in murine leukaemia cells with viral integration in the EVI1 locus and in human leukaemias with chromosome 3q abnormalities [10,11,12,13,14,15]. Here, MECOM is linked to leukemia.