DUSP4 and infection: While LPS/IFN-γ activation stimulated NO production, as measured by nitrite production 72 hours post-infection in the supernatants of T. gondii infected MKP-2−/− and MKP-2+/+ macrophages, this was significantly higher in the infected MKP-2+/+ culture supernatants (p<0.0001) (Figure 7B).