FGF2 and leukemia: However, recent evidence suggests that there is little direct association between osteoblasts and HSCs15, 16 in accordance with in vitro results that FGF2-treated 7F2 cells showed limited supportive functions toward leukemia cells (Figs 1b and 2b), even though leukemic stem cells localize within the osteoblast-rich (endosteal) area of the BM where acute myeloid leukemia cells are protected from chemotherapy-induced apoptosis17.