Aurora and IKK kinases interact in MM cells. (A) RPMI 8226/R5 were treated with PHA-680632 for 3 hours and then incubated with TRAIL (9.6 ng/mL). After 24 hours of treatment, cells were lysed in CHAPS lysis buffer and subjected to immunoprecipitation (IP) using mouse monoclonal IKKα (B-8), mouse monoclonal IKKβ (H-4), mouse monoclonal ARK-1 (35C1) (Aurora A), mouse monoclonal ARK-2 (13E8A7) (Aurora B), or control antibody (IgG) and immunoblotted (IB) with Aurora A or Aurora B or IKKα and IKKβ antibodies. Bands were subjected to densitometric scanning, and the histogram shows average quantification results ± SD of the association Aurora A/IKKα, Aurora A/IKKβ, Aurora B/IKKα, or Aurora B/IKKβ from 3 blots (*P < .01, vs untreated control cells, Tukey-Kramer test). (B) HMCLs were cultured with pan-AKIs and/or TRAIL as previously reported for 24 hours. Endogenous phospho-Aurora A (Thr288) and phospho-Aurora B (Thr232) from whole cell lysates were revealed by western blot analysis. Anti-actin immunoblotting was performed as loading control. The relative amount of phospho-Aurora A (Thr288) and phospho-Aurora B (Thr232) was determined by densitometry and normalized to that of actin. Histograms represent the mean ± SD of the ratio phospho-Aurora A (Thr288)/actin or phospho-Aurora B (Thr232)/actin normalized to the untreated control from blots of 3 separate experiments.