Consistently, KD of SMAD2 or SMAD4 by siRNA had no effect on the phosphorylation of NF-κB p65 whereas TAK1 KD (with and without SMAD2 KD) suppressed the phosphorylation of NF-κB p65 in rTGF-β1-treated NB cells (Fig. 3c). This evidence concerns the gene SMAD4 and neuroblastoma.