HOXD9 and Ewing sarcoma: We and others have shown that the posterior HOXD genes, HOXD9, HOXD10, HOXD11, and HOXD13 are overexpressed by Ewing sarcoma [15, 35] and that the promoters of these genes are devoid of the repressive H3K27me3 mark and highly enriched with the MLL-mediated H3K4me3 mark [15, 21].