FIGURE 6.

JLP deficiency selectively attenuates CD154-triggered activation of the MAPK (but not NF-κB) signaling pathway in B lymphocytes. A, purified splenic B lymphocytes from jlp^+/+ and jlp^−/− mice were left untreated (0 min) or were treated with rCD154 (1 μg/ml) at the indicated time points. Cells were harvested, and whole-cell lysates were electrophoresed and analyzed for total ERK, p38, JNK, and relevant phosphorylated (p) forms of ERK, p38, JNK, c-Jun, and IκBα by immunoblotting. Equal protein loading was controlled by actin staining. B, purified splenic B lymphocytes from jlp^+/+ and jlp^−/− mice were stimulated with anisomycin (250 ng/ml) at the indicated time points. Whole-cell extracts were analyzed by immunoblotting as described above. Wild-type B lymphocytes were pretreated with or without ciliobrevin D (50 μm) for 30 min and left unstimulated (0 min) or stimulated with rCD154 (C) or anisomycin (D) at 15 min and 30 min. Cells were then harvested, and the extracts were analyzed by immunoblotting as described above. Expression of the phosphorylated molecules was normalized to the indicated total molecule expression or β-actin. Means ± S.D. were collected from at least three independent experiments. Error bars indicate S.D. *, p < 0.05 (two-tailed Student's t test).