KITLG and acute myeloid leukemia: Exosomes derived from Acute Myeloid Leukemia (AML) caused downregulation of the expression of stromal cell factor (SCF) and CXCL12 in stromal cells, both important for normal hematopoiesis which leads hematopoietic stem/progenitor cells (HSPCs) to leave the bone marrow (Huan et al., 2015; Yang et al., 2019).