VEGFA and acute myeloid leukemia: Exosomes released by AML cells upregulate DKK1 in BM mesenchymal stromal cells and thereby inhibit normal hematopoiesis through the WNT signaling pathway, and AML-derived exosomes stimulate vascular endothelial growth factor (VEGF) signaling in human umbilical vein endothelial cells (HUVECs) by transferring angiogenic factors or proteins and miRNAs, which form vascular tubular structures that promote tumor growth (4, 67).