Trunk cleavage is essential for Drosophila terminal patterning and can occur independently of Torso-like

Terminal patterning of the Drosophila embryo is thought to be regulated by local cleavage of the ubiquitous peptide hormone Trunk (Trk) controlled by the maternal gene torso-like (tsl) that is expressed only at embryo poles. Here, the authors show that cleavage of Trk is indeed required for patterning and can occur independently of Tsl.