endocytic pathway is required for drosophila toll innate immune signaling the toll signaling pathway is required for the innate immune response against fungi and grampositive bacteria in drosophila here we show that the endosomal proteins myopic mop and hepatocyte growth factorregulated tyrosine kinase substrate hrs are required for the activation of the toll signaling pathway this requirement is observed in cultured cells and in flies and epistasis experiments show that the mop protein functions upstream of the myd88 adaptor and the pelle kinase mop and hrs which are critical components of the escrt0 endocytosis complex colocalize with the toll receptor in endosomes we conclude that endocytosis is required for the activation of the toll signaling pathway