BLyS stimulates NF-κB activation. (A) After cell stimulation with 200 ng/mL _LBLyS for each indicated time point at 37°C, cell extracts were analyzed for IκBα degradation. Unstimulated cells were used as a control (bottom panel). (B) Cells were stimulated with 200 ng/mL _LBLyS or 20 ng/mL LPS for 30 minutes ± 10 or 50 μg/mL polymyxin B (PB), and cell lysates were immunoblotted for IκBα. (C) Cells were stimulated with the indicated concentrations of _SBLyS or LPS for 30 minutes ± 50 μg/mL polymyxin B before analysis of IκBα levels by immunoblotting. (D) Cells were stimulated as described in panel A, and cell lysates were analyzed for p52 expression levels. β-Actin was used as a loading control in all experiments.