CD40 induces NF-κB activation in a PI3K-dependent manner.

(A) Serum-starved MM.1S cells were stimulated with 2 μg/mL G28.5 anti-CD40 mAb, and total cell lysates were made at the indicated time points. Western blotting was performed using an anti-IκBα Ab. The same blot was stripped and probed for tubulin to confirm equal loading. (B) Serum-starved MM.1S cells pretreated with PI3K inhibitor LY (0-30 μM) were stimulated with CD40, and Western blotting using an anti-IκBα Ab was performed. Again immunoblotting with anti–α-tubulin served as a control loading.