Unexpectedly, the antiproliferative effect of PI3K inhibition was more pronounced in BCR-ABL negative ALL cells: At concentrations close to the IC50, LY294002 and NVP-BKM120 inhibited proliferation by a median of 30% in ALL with an ABL-translocation (BCR-ABL+/TEL-ABL+) and by 50% and 55% in BCR-ABL negative cells (p=0.022 for NVP-BKM120) (Figure 3A). This evidence concerns the gene PIK3CA and acute lymphoblastic leukemia.