Cell migration contributes to morphogenesis and organ formation during embryogenesis. In Drosophila a number of cell groups undergo migrations over large distances. The blood cells (hemocytes) originate from the anterior mesoderm and distribute from there in the entire embryo where most of them later act as macrophages. Another prominent group of migrating cells are the precursors of the longitudinal muscle fibers surrounding the midgut. These precursors originate from the caudal visceral mesoderm (CVM) and migrate to distribute over the midgut.
Using the migration of hemocytes as a model we have identified molecules which execute and regulate cell migration and cell motility by means of a so-called EP-screen.