To test the role of stromal Fgf2 in an in vivo leukemia model, bone marrow from Fgf2 +/+ mice was retrovirally transfected with BCR-ABL containing GFP as a marker (Traer et al., 2012) and used to transplant lethally irradiated FGF2 +/+ and -/- mice. This evidence concerns the gene BCR and leukemia.