Silencing IL-12p40 influences IFN-γ protein expression. The influence of silencing IL-12p40 on the expression of IFN-γ was determined using the conditions described in Fig. 1, by sqRT-PCR for IFN-γ mRNA (A) or by ELISA for IFN-γ protein present in culture supernatant (B). Data are representative of at least four independent experiments; IFN-γ protein concentration is expressed as the mean (+/-SEM) from triplicate cultures (n = 3) on each occasion. Levels of IFN-γ are significantly reduced in the presence of IL-12p40 siRNA for 24, 48, and 72 h (p < 0.0001) when compared to stimulated non-silenced cultures.