Co-cultures of AML cells harboring internal tandem duplication of FLT3 (FLT3-ITD) together with MSCs protect blasts from FLT3 inhibitors through the alteration of cytokines, chemokines, RAS/MAPK, and ERK signaling pathways.29 However, the precise population of cells and molecular mechanisms involved in chemoresistance have only been partially elucidated. Here, FLT3 is linked to acute myeloid leukemia.