Basal and BCR-induced EGR-1 expressions are dependent on JNK activation. (A) Primary cells (UPN9) were pretreated with SP600125 (10 μM) for 1 hour and then stimulated with soluble anti-IgM antibody (10 μg/ml) for 5 min. Basal and BCR-induced phosphorylation of JNK (p54 and p46) were analyzed by western-blot. ns: non specific band. (B) Treatment with SP600125 led to a time-dependent decrease of mRNA and protein EGR-1 levels in Granta-519 and HBL-2 cells. (C) Impact of SP600125 on BCR-induced EGR-1 expression. Granta-519, HBL-2 and primary cells (UPN1) were pretreated with SP600125 for 1 h and then stimulated with immobilized anti-IgM antibody. EGR-1 mRNA and protein levels were analyzed by qRT-PCR and western-blot respectively. Fold increase of mRNA level were calculated relative to unstimulated cells in all experiments. All measurements were done in duplicate and the mean is provided.