Nuclear factor (NF-kappaB)(1) is a eukaryotic transcription factor that may be activated by oxidative stress. Because of this hypothesis, the effect of vitamin E on NF-kappaB activation has been examined in many studies, using both in vivo and in vitro models. Most of these studies have observed that vitamin E inhibits the activation of NF-kappaB, with the greatest inhibition seen with the succinate form. Vitamin E may be inhibiting NF-kappaB by reducing oxidative stress or through one of its nonantioxidant functions; this is not clear at the present time. It also is not known if the inhibition of NF-kappaB is necessary for any of vitamin E's effects on gene expression and the resulting physiological effects.