Effect of inhibitors and IKB-sr on phosphorylation of ERK and p70S6 kinase and on NF-kB activation.

(A) Mutant N-ras cells were depleted of IL-6 for 48 hours and then incubated without (control) or with FTI-277 at varying concentrations for 24 additional hours. Immunoblot assay was then performed for phosphorylated ERK (top) and phosphorylated p70S6 kinase on threonine 389 (bottom). Immunoblot assay for total ERK and p70 demonstrated equal expression in all lanes (not shown). (B) EMSA experiment shown for IL-6–depleted (48 hours) mutant N-ras cells either not infected (control) or infected with adenovirus expressing IKB-sr (Ad-IKB-sr) or empty vector (Ad-CMV) at an MOI of 50.