Using a transient transformation strategy, midgut-specific overexpression of the same mutated MEK allele in vivo reduced ERK phosphorylation in this tissue and reduced development of naturally acquired Plasmodium berghei in vivo, suggesting for the first time that tissue-specific overexpression of mutated MEK could be used as the basis for a malaria transmission blocking strategy. The gene discussed is MAPK1; the disease is malaria.