These authors elegantly showed that treatment of BMMSCs with AML cell-derived exosomes decreases the expression of genes that control osteoblast maturation (OCN, Col1A1, IGF1) and support normal haematopoiesis (CXCL12, KITL, IL-7, IGF1) while increasing the expression of genes supporting AML growth (DKK1, IL-6, CCL3). The gene discussed is DKK1; the disease is acute myeloid leukemia.