Morphogens and endocytosis

During development, secreted signaling proteins of the Wingless/Wnt, Hedgehog and Decapentaplegic (Dpp)/Bone Morphogenic Protein (BMP) families act as morphogens. Previous work had shown that these molecules act directly on distant cells, although until recently nothing was known about how they reach those distant cells. During the past two years, work carried out on Drosophila using genetic and cell biology approaches have revealed that endocytosis plays a central part in the mechanisms that control the spread of morphogens.