CYBB, CYBA, NCF-1, and NCF-2 gene expression in U937 cells induced to differentiate by IFN-γ and TNF-α. (A and C) respective down-regulation of CYBB and NCF-1 transcript levels in the U937 subclone transfected with IκB S32A/S36A, compared with the wild-type and U937 cells transfected with empty vector (*P < .05 in all situations; n = 4, Mann-Whitney test). (B) CYBA gene expression was not affected. (D) NCF-2 gene expression was not significantly inhibited by transfection with IκB S32A/S36A (P > .05 in all situations; n = 4, Mann-Whitney test).