During TGF-ß signaling, Sara acts as a scaffold protein recruiting the transcription factor to the ligand receptor. Sara is a member of the TGF-ß super family, which associates to endosomes by binding PtdIns(3)P. Sara endosomes are involved in the symmetric partitioning of TGF-ß/BMP signaling molecules during wing development and in the asymmetric distribution of Delta and Notch during SOP asymmetric cell division. We still do not know what mechanisms are involved in Sara endosomal dynamics and trafficking. During my PhD I focused on finding the molecules, which drive the targeted motility of Sara endosomes during SOP asymmetric cell division. Other key questions were i) how Notch and Delta are targeted into Sara endosomes during SOP division,? and ii) what are the Activin target genes during Sara-mediated TGF-ß Signaling? In order to answer these questions, the main goal of my PhD has been to unravel the Sara machinery.