The tracheal system of arthropods is a complex tubular network which is necessary for the gas exchange. It’s systematically spread through the organism to enable the required oxygen supply. In Drosophila larvae a central tracheal tube, coated with an apical membrane, ranges the body. The detailed mechanism of its formation is still unknown, whereas Dong et al. searched for Drosophila mutants whose dorsal trunk (DT) is altered. They observed an elongated and wavy tracheal tube in shrub mutants. The shrub gene encodes a subunit of the endosomal sorting complex required for transport III (ESCRT III), which is necessary for membrane deformation, internalization and scission. To study the cause of the abnormal elongation they performed different reporter gen assays and immunohistochemical stainings and investigated that the apical surface amount was increased in shrub mutants. Their results illustrate that the shrub mutation promotes the overgrowth of the DT apical membrane. To identify possible downstream processes controlled by shrub Dong et al. focused on the known membrane determinant Crumbs (Crb). In the shrub mutant, Crb was delocalized and formed cytoplasmic aggregates at the endosomal membrane and also the Crb level was increased in comparison to the wildtyp. They speculated whether the delocalized and upregulated Crb activity stimulates apical membrane overgrowth and thereby the elongated DT. To examine this hypothesis, they reduced the Crb level in a shrub mutant by knocking out one allele of crumbs. Indeed, the DT phenotype was less elongated and less wavy. Recent studies had shown, that the tyrosine protein kinase Src42A promotes the apical membrane growth in DT cells and the anteriorposterior axis orientation. In this work Dong et al. newly investigated that Shrub is also part of the apical membrane formation by regulating Crp. These results allow a more detailed knowledge about the tracheal formation but further research is still needed. Aufbau insgesamt in ordnung. Viele redundante Aussagen und Sätze. Kürzen bitte.