FIG. 4.

Bortezomib inhibits NF-κB activity in LCLs. LCLa cells were cultured in the absence or presence of 1μM bortezomib for 2 h (A) or 4 h (B), and nuclear extracts were used in electrophoretic mobility shift assays with a radiolabeled NF-κB probe. Specific or nonspecific nonradioactive competitor oligonucleotides were added in some assays. (C) Mutu I, Mutu III, LCLa, LCLb, and BJAB cells were analyzed by electrophoretic mobility shift assays for NF-κB as described for panel B, and the reduction of NF-κB in cells treated with bortezomib for 4 h relative to the level in untreated cells is shown. Data for LCLa was derived from panel B. (D) LCLa cells were incubated in the absence or presence of 1 μM bortezomib (bort) for the time periods indicated above each lane, and proteins from whole-cell extracts were immunoblotted with anti-phosphorylated IκBα and anti-IκBα antibodies. Anti-β-actin antibody was used as a protein loading control.