Septins are cytoskeletal GTP-binding proteins involved in processes characterized by active membrane movement, such as cytokinesis, vesicle trafficking and exocytosis. Most septins are expressed ubiquitously, however, some septins accumulate in particular tissues. The ubiquitous SEPT11 also shows high expression levels in the central nervous system and in platelets. Here, SEPT11 is involved in vesicle trafficking and may play a role in synaptic connectivity. Interestingly, mice that harbor a homozygous Sept11 null mutation, die in utero. From day 11.5 post coitum onwards, development of homozygous embryos seems to be retarded and the embryos from day 13.5 onwards were dead.