TRAIL DcR2 knockdown or proteasome inhibitor treatment inhibits NF-κB activation in LGL leukemia cells. (A) TL-1 and NKL cells were transfected with DcR2-specific siRNA (100 nM) or scramble siRNA by electroporation. Cells were kept in culture for 72 hours. The expression of DcR2, TRAF2, NF-κB p65, phosphorylated p65, and NF-κB p50 was determined by western blot immunoassay. (B-C) TL-1 cells (B) and NKL cells (C) were treated with bortezomib (5 nM), ixazomib (100 nM), or vehicle (dimethyl sulfoxide [DMSO]), and protein samples were harvested at different time points as indicated. The expression of TRAF2, phosphorylated IKK α/β, IKK β, NF-κB p65, phosphorylated p65, and NF-κB p50 was determined by western blot immunoassay. β-Actin was used as a control for equal loading. (D) PBMCs from T-LGL leukemia patients were treated with bortezomib (5 nM) or ixazomib (100 nM) for 24 hours. The expression of TRAF2, phosphorylated IKK α/β, NF-κB p65, phosphorylated p65, and NF-κB p50 was determined by western blot immunoassay. β-Actin antibody was used as a control for equal loading.