BCR activation significantly enhances eIF4A cap-binding activity in human splenic B cells. (A) Protein lysates from human splenic B cells were harvested 24 hours after treatment with Isotype, anti-BCR, anti-CD40, or anti-BCR+CD40 and then analyzed by western blot analysis for p-4EBP1 (Thr36/37), total 4EBP1, PIM2, p-p70s6K (Thr389), total p70s6K, p-EIF4B (Ser406), total EIF4B, p-RPS6 (Ser235/236), RPS6, p-PDCD4 (Ser67), and total PDCD4. GAPDH served as a loading control, and data are representative of 3 independent experiments. (B) Lysates were incubated with m7GTP Sepharose beads overnight at 4°C. Western blot analysis was used to observe eIF4A, eIF4G, and eIF4E binding to m7GTP. Data are representative of 3 independent experiments (3 individual spleens).