CEP-18 770 modulates the NF-κB signaling pathway in human MM cell lines. (A) RPMI-8226 cells were pretreated with control solvent (dimethyl sulfoxide; DMSO) or CEP-18770 (20 nM) for 6 hours before stimulation with TNF-α (10 ng/mL) for the indicated times. Whole cell extracts were immunoblotted with anti-IκBα and phosphorylated IκBα (P-IκBα) to assess IKK-mediated NF-κB activation. α-tubulin immunoblotting was included for protein loading normalization. (B) Whole-cell extracts were analyzed for NF-κB activation by electrophoretic mobility shift assay (EMSA). A section of the fluorogram is shown. (C) RPMI-8226, U266, and K562 cells were treated with CEP-18770 (20 nM) or BOR (10 nM) and immunoblotted with the specified antibodies to detect levels of total IκBα, P-IκBα and XIAP proteins. (D) U266 cells were treated with control diluent, CEP-18770 (20 nM), or BOR (10 nM) for 12 hours. Levels of ICAM1, TNF-α, IL1β, VEGF, and β2-microglobulin mRNA were analyzed by semiquantitative RT-PCR.