Figure 2. PI3K p110 isoform inhibitors inhibit macropinocytosis.

(A) Fixed-cell imaging of MP formation following treatment with inhibitors. FDx-positive vesicles (MPs) are labeled with red overlay. CXCL12 treatment induced MP formation. Compared with the +CXCL12 sample (CXCL12), cells treated with a combination of p110δ and p110γ inhibitors (CXCL12+γ/δ) or a combination of p110α and p110β inhibitors (CXCL12+α/β) contained few or no MPs. Original scale bars, 10 μm. (B) Quantification of the MP assay. Partial inhibition of pinocytosis was evident when cells were treated with the p110γ inhibitor (AS252424), p110δ inhibitor (IC87114), p110α inhibitor (A66), or p110β inhibitor (TGX221) independently. When used in combination, however, the cocktail of p110γ/δ inhibitors or p110α/β inhibitors yielded nearly complete inhibition of macropinocytosis (*P < 0.05). More than 75 cells from 3 independent experiments were observed.