Cell-permeable. A potent, selective and ATP-competitive inhibitor of PI 3-kinase β (IC₅₀ = 5 nM for p110β). Inhibits other PI3K isoforms at higher concentrations (IC₅₀ = 0.1 µM for p110δ, 5 µM for p110⍺, and 3.5 µM for p110ɣ).