MAPK3 and infection: Based on the hypothesis that the shutdown of ERK1/2 phosphorylation around the 5th week of infection is critical for further alterations on the course of L. amazonensis infection, and progressive disease, we tested whether administration of U0126, earlier than at the 5th week of infection, would anticipate the onset of lesion development and the increase parasite loads and inflammatory responses in L. amazonensis infected mice.