Therefore we set out to determine the molecular regulation of HSCs by Stat5 and understand whether the context of defective hematopoiesis in the absence of Stat5 could predispose toward initiation or progression of a classic non-Stat5 dependent Eμ-Myc/H2K-Bcl-2 driven murine B-lymphoblastic leukemia (B-ALL). Here, BCL2 is linked to precursor B-cell acute lymphoblastic leukemia.