The role of nuclear factor kappa B (NF-kappaB) in oxidative stress, and most recently in pro- and anti-apoptotic-related mechanistic pathways, has well been established. Because of the dual nature of NF-kappaB, the wide range of genes it regulates and the plethora of stimuli that activate it, various studies addressing the functional role of NF-kappaB proteins have resulted in a number of differing findings. The present study examined the effect of a stimulus-free environment on the frontal cortex of mice brain with the p50 subunit of NF-kappaB knocked out p50 (-/-). Homozygous p50 mice knockout (KO) and wild type (WT) were used, and at 7-9 weeks they were sacrificed and various brain regions dissected. We analyzed the levels of oxidation in the frontal cortex of both the p50 (-/-) and WT mice. There was a significant reduction in the levels of protein-bound 4-hydroxynonenal (HNE) [a lipid peroxidation product], 3-nitrotyrosine (3NT), and protein carbonyls in the p50 (-/-) mice when compared to the WT. A proteomic profile analysis identified ATP synthase gamma chain, ubiquinol-cyt-C reductase, heat shock protein 10 (Hsp10), fructose bisphosphate aldolase C, and NADH-ubiquinone oxidoreductase as proteins whose expressions were significantly increased in the p50 (-/-) mice compared to the WT. With the reduction in the levels of oxidative stress and the increase in expression of key proteins in the p50 (-/-) brain, this study suggests that the p50 subunit can potentially be targeted for the development of therapeutic interventions in disorders in which oxidative stress plays a key role.