Since we observed up regulation of HSP70 due to induction of oxidative stress and inhibition of HSP90 activity, one possible mechanism through which withanolides inhibit NF-kB activation in NB cells may be via suppression of nuclear translocation of NF-κB through attenuation of serine 536 phosphorylation of p65. This evidence concerns the gene NFKB1 and neuroblastoma.