BEZ235 (NVP-BEZ235) is a dual inhibitor of the PI3K and the downstream mammalian target of rapamycin (mTOR) by binding to the ATP-binding cleft of these enzymes. It inhibited the activation of the downstream effectors Akt, S6 ribosomal protein, and 4EBP1 in breast cancer cells. For Class I PI3K family, its biochemical IC50 is 4nM against p110α, 75nM against p110β, 7nM against p110σ, 5nM against p110γ. Quantification of S473-Akt and T308P-Akt levels by ELISA revealed that 50% reduction occurred at a compound concentration of 8.0 nM and 30 nM.