Haploinsufficiency of the CUX1 homologue (cut) leads to hematopoietic overgrowth and formation of melanotic pseudo-tumors in Drosophila melanogaster. Larvae (right) and pupae (left) develop abnormal black masses (outlined by red squares) upon cut knockdown. Punctate GFP+ hemocytes can be appreciated in the larval stage. CUX1 is frequently deleted in high-risk acute myeloid leukemia and haploinsufficient levels lead to increased growth of human hematopoietic cells, demonstrating the conservation of CUX1/cut from invertebrates to humans. Figure illustration was designed by Dimitri Novikov. See the article by McNerney et al on page 975.