Abstract: The ability to polarize is one of the key functional features of virtually every cell in a multicellular organism, such as a human being. For example, in the intestine, the cell surface facing the lumen must absorb nutrients, while the opposite surface must secrete them into the blood stream. In another example, during the development of a blood vessel, the tip cell of a growing capillary should extend its front edge in a specific direction. The executors of cell polarity programs are the filaments of the cell skeleton (cytoskeleton), which form asymmetric networks. One of the major cytoskeletal components are microtubules, microscopic hollow tubes that serve as rails for transport of different cellular components. In my seminar, I will discuss how cells build symmetric and asymmetric microtubule networks and use them to drive cell polarity in different cell types.