Effective suppression of PI3K signaling utilizing two potent, dual specificity ATP-competitive compounds, both of which are pan-PI3K inhibitors and additionally block the mTOR complexes C1 and C2 downstream of PI3K (NVP-BGT226 and NVP-BEZ235), potently inhibits proliferation and induces cell death in BCR-ABL positive and in TEL-ABL positive ALL at nanomolar concentrations. This evidence concerns the gene BCR and acute lymphoblastic leukemia.