Apoptosis induced by TAK1 inhibition is mainly dependent on NF-κB pathway. (A) OCI-M3 cells were treated with various concentrations of 5z-7-oxozeaenol, and western blot analysis was performed on phospho-IκBα, total IκBα, phospho-ERK, total ERK, phospho-c-JUN, total C-JUN, phospo-p38, and total p38. (B) NF-κB activity of OCI-M3 cells treated with 100 nM 5z-7-oxozeaenol. NF-κB activity was measured by p65 DNA-binding enzyme-linked immunosorbent assay. The negative control is the background (no nuclear extract). (C) MOLM13, OCI-M3, and HL60 cells were treated with 10 μM JNK inhibitor SP600125, 5 μM MEK/ERK inhibitor U0126, 5 μM NF-κB inhibitor BMS-345541, or 1 μM p38 inhibitor SB203580, alone, or in combination with TNFα. After 24 hours of incubation, apoptosis was quantified by annexin V staining. (D) OCI-M3 cells were transduced with control MIGR1 or IKK SSEE vector and incubated with 80 nM AZ-TAK1. After 24 hours, annexin V⁺ cells were measured. (E) Relative cFLIP_L levels of SCR HL60 and shTAK1 cells were quantified by quantitative polymerase chain reaction. MSCV, murine stem cell virus.