GDF15 and leukemia: After demonstrating the presence of CAFs in the marrow microenvironment of primary AML and their ability to protect leukemia cells from chemotherapy agents in vitro, we assessed whether GDF15 contributed to the CAF-mediated chemo-protection of AML cells either by using a neutralizing anti-GDF15 antibody or by knocking down GDF15 (siGDF15) in the CAFs as well as by investigating the distribution of GDF15 in the cytoplasm of CAFs within BM sections from AML patients.