Cells are characterized to be stable yet highly flexible. They constantly modify their shape and even move through tissue. These vital properties are based on a dynamically organized network of branched actin filaments, which generates pushing forces to move the cell membrane. An interdisciplinary team lead by Peter Bieling and Stefan Raunser from the Max Planck Institute of Molecular Physiology (MPI) in Dortmund has now revealed a previously unknown mechanism, explaining how stopping the growth of older actin filaments within the network promotes the formation of new ones, thereby maintaining the structure and function of the cytoskeleton, much like proper pruning of hedges in the garden.