Cell-cycle regulator c-Myc and prosurvival transcription factor Egr-1 are downstream of JNK signaling in B-lymphoma cells. (A) WEHI-231 B-lymphoma cells were incubated with medium, 10 μM SP600125, and anti-CD40, either alone or in combination for the indicated time periods. Cell lysates were analyzed by immunoblotting with an antibody to c-Myc. The blots were then stripped and probed with anti-β-actin antibody to correct for changes in protein loading in different lanes. (B) Immunoblotting of lysates from control or JNK-specific siRNA-transfected WEHI-231 cells with antibodies to c-Myc and β-actin. (C) BKS-2 B-lymphoma cells were incubated with medium or 10 μM SP600125 for the indicated time periods. Cell lysates were analyzed by immunoblotting with an antibody to Egr-1 and then stripped and probed for β-actin. (D) WEHI-231 B-lymphoma cells were treated with control or JNK-specific siRNA for 24 hours. Cell lysates were analyzed by immunoblotting with an antibody to Egr-1 and then stripped and probed for β-actin. (E) Flow cytometry analysis of SP600125- or vehicle (DMSO)-treated BKS-2 cells with an antibody to ICAM-1. Flow cytometry was performed as described in “Materials and methods.” Numbers indicate the ratio of density of c-Myc to β-actin in panels A and B and of Egr-1 to β-actin in panel C. Experiments were done 2 to 3 times with similar results.