SDX-308 inhibits NF-κB activation signaling in MM cell line MM.1S cells. MM.1S MM cells were incubated with drug vehicle, SDX-101, or SDX-308 for 1 hour, treated with TNF-α (20 ng/mL) for 15 minutes, and then lysed. NE and CE were prepared as described in Figure 6. (A-B) Phospho-p65 and IκB-α in CE and p65 in NE were detected by Western blot assay. (C-E) MM.1S cells were treated with drug vehicle, SDX-101, and SDX-308 for 1 hour and then stimulated by TNF-α in the presence of calyculin A (50 nM) for 15 minutes. Phospho-IκB-α, IκB-α, and phospho-IKK-γ in whole cell lysates were detected using the respective antibody. (A-E) β-Actin served as loading control.