The effect of TRAF5 deficiency on LMP1-mediated JNK activation and IL-6 secretion in vitro. Splenic B cells were purified from LMP1+TRAF5+/+ and LMP1+TRAF5−/− mice of 8–12 weeks of age by negative selection (>95% purity). Purified B cells were stimulated with 5 μg/mL anti-mCD40 (HM40.3), 5 μg/mL isotype control, or 100 ng/mL CpG-B (2084) in 48-well plates, and at 48 h their supernatants were collected for use in an IL-6-specific ELISA (A). Purified B cells were stimulated in vitro with 10 μg/mL anti-mCD40 (HM40.3), 10 μg/mL isotype control, or 100 ng/mL CpG-B (2084) for 20–90 min and used in a phospho-JNK Western blot (B). P-JNK was normalized to total JNK (C), P-IκBα was normalized to total IκBα (D), and total IκBα was normalized to actin (E). *, P < 0.001.