HOXA9 and myeloid leukemia: Interestingly, we found that the expression of Myb, a helix-turn-helix transcription factor important for hematopoietic development and a critical target for Hoxa9-induced myeloid leukemia development [16], was up-regulated to similar levels in Hoxa9+BCR/ABL and Hoxa10+BCR/ABL leukemias (Supplementary Figure 2), suggesting that Myb could be a shared critical target of Hoxa9 and Hoxa10 in their stimulation of self-renewal.