tokens: Since internal sites of oxidant production have been shown to play a key role in the cytokine -stimulated activation of NF-kappa B , and since tyrosine kinase and phosphatase activities are known to be altered by oxidants , these findings suggest that intracellular redox status controls NF-kappa B activation by regulating tyrosine phosphorylation event ( s ) within the common step of the NF-kappa B signal transduction pathway .