FIG. 5.

PS-341 treatment leads to an activation of the NF-κB pathway and JNK/AP-1 pathway. (A) A549, Vero, MDCK II, HEK293, HUVEC, and HBEpC cells were treated with 50 nM PS-341 for the indicated times or left untreated. In addition, cells were stimulated with 30 ng/ml TNF-α for 15 min or left unstimulated. Cell lysates were subjected to Western blot analysis against IκBα and phosphorylated p65 (Ser536). p65 and ERK2 served as controls for equal protein amounts. (B and C) A549 cells were treated with PS-341 at 50 nM for the indicated times or left untreated. (B) Western blotting was performed with total cell lysates, using phospho-specific antibodies against JNK and the transcription factors c-Jun and ATF-2 or loading controls, respectively. (C) Native PAGE analysis was performed with total cell lysates to detect IRF-3 dimers. As a control for IRF-3 dimerization (ctr.), A549 cells were transfected for 4 h with 1 μg RNA isolated from FPV-infected A549 cells (MOI of 5; 5 h). In each case one representative blot is shown of three independent experiments.