Figure 2. X-370 is highly selective against PI3Kδ-mediated signaling at cellular level.

(A) The panel of isogenic Rh30-Myr-p110α, Rh30-Myr-p110β, Rh30-Myr-p110γ and Rh30-Myr-p110δ cells were cultured in serum-free medium for 12 h and then incubated with serially diluted X-370 for an additional 1 h. Cell lysates were probed with indicated antibodies. The IC₅₀ values were calculated based on relative band intensity measured with ImageQuant™ TL (GE Healthcare Life Sciences, Piscataway, NJ) (B). Data shown are mean values from three independent experiments. (C, D, E, F) X-370 blocked stimuli-triggered PI3Kδ activation. MEF cells and THP-1 were starved in serum-free medium for 12 h or 4 h respectively and X-370 were added for an additional 1 h treatment following stimulation of IGF-1 at 100 ng/ml for MEF cells (C), LPA at 10 μM for MEF cells (D), MCP-1 at 100ng/ml for THP-1 (E) and M-CSF at 50 ng/ml for THP-1 (F). Similar results were derived from 3 independent experiments.