NAC and IFN synergistically inhibit p65 expression in HepG2 and Huh7 cells. Quantification of band density with an imaging densitometer. Results are representative of three independent experiments. Values are shown as means and standard errors of the mean (SEM).a- NAC x CO p<0.01. b- NAC+IFN x CO x IFN x NAC p<0.01.