Effect of overexpression of NIK and IKK-β in cell lines with low NF-κB index. (A) Overexpression of IKK-β activates classical NF-κB pathway. Immunoblot of MMCLs after infection with empty vector or constitutively active IKK-β gene. Nuclear and cytosol extracts were prepared, and expression of the proteins indicated at right was analyzed. (B) Activation of NF-κB target gene expression after infection of cells with NIK or IKK-β. Average of 11 target gene expression in cells infected with NIK or IKK-β corrected by subtraction of expression in cells infected with empty vector. Data are mean ± SE.