BCR activation enhances protein translation in human splenic B cells. (A) Protein lysates from human splenic B cells were harvested 30 minutes after treatment with either Isotype, anti-BCR, anti-CD40, or anti-BCR+CD40 and then analyzed by western blot analysis for p- Igα (Tyr182), total Igα, p-CD40 (Thr254), and total CD40. (B) Lysates were harvested and analyzed for p-ERK (Thr202/Tyr204), total ERK, p-PDK1 (Ser241), total PDK1, p-MTOR (Ser2448), and total MTOR. GAPDH served as a loading control, and data are representative of 3 independent experiments. (C) Human splenic B cells were harvested, washed, and stained for CD69 24 hours after activation. Fluorescence-activated cell sorter analysis was used to quantify the surface CD69 expression. Data are means ± standard error of the mean (SEM) of 3 independent experiments. (D) Cells were incubated with 1 mCi L-[³⁵S]methionine and l-[³⁵S]cysteine 24 hours after treatment, and lysates were harvested and analyzed for radiolabel incorporation. Densitometry was used to quantify radiolabel incorporation, and data are means ± SEM of 3 different experiments (3 individual spleens; *P < .05).