BGT226, BKM120 and RAD001 inhibit phosphatidylinositol-3-kinase pathway signaling in breast cancer cells. Western blots showing effects of (a) BGT226, (b) BKM120 and (c) RAD001 dose escalation on p-Ser473 Akt (p-Akt) and p-Ser235/236 S6 (p-S6) in breast cancer cell lines. Cells were stimulated with 20% fetal bovine serum (15 minutes) in the presence of solvent (dimethylsulfoxide (DMSO), BGT226-treatment only) or the indicated concentrations of phosphatidylinositol-3-kinase (PI3K) inhibitors. LY294002 (LY, 20 μmol/l) and rapamycin (100 nmol/l) were used as controls in the BGT226 treatment panel for total PI3K inhibition (LY) and mammalian target of rapamycin inhibition (rapamycin). Total Akt, S6 and actin are shown as loading controls. Representative results obtained in at least two experiments per cell line per drug treatment are shown.