However, whereas MKP-2−/− macrophages classically activated with LPS and IFN-γ failed to reduce L. mexicana parasite burdens to the level of similarly treated MKP-2+/+ macrophages [21] such treatment sufficed following infection with L. major promastigotes to ablate any differences in susceptibility between MKP-2−/− and MKP-2+/+ host cells (Figure 2B) and corresponded to LPS and IFN-γ treatment ablating the deficiency in NO production in MKP-2−/− macrophages infected with L. major (data not shown). Here, DUSP4 is linked to infection.