HOXA9 and acute myeloid leukemia: To identify genes co-expressed with IRX3 in human AML, we next compared IRX3high AMLs (probeset 229638_at value of log2 > 7.1) with IRX3low AMLs (probeset 229638_at value of log2 < 6.1) (Wouters et al., 2009) and found HOXA9 and HOXA5 to be the most differentially expressed transcription factor genes in the IRX3high group whether (data not shown) or not (Figure 1E) cases of APML (which do not express HOX genes) were included.