Whether you're going on holiday or just travelling to work, life involves a lot of moving around. And this dynamic process is important at the cellular level too, as three articles in this issue show. On page 246, Tom Rapoport and colleagues review the poorly understood process of retro-translocation, which transports misfolded proteins from the endoplasmic reticulum to the cytosol for destruction. Erik Christensen and Henrik Birn (page 256) discuss megalin and cubilin, two endocytic receptors that have important transport functions in several absorptive epithelia. And on page 267, David James and co-workers review the translocation of the glucose transporter GLUT4, a process that could be essential for whole-body glucose homeostasis.

But transport is not the only dynamic process essential for life, and sometimes you don't actually need to move to be dynamic. Take the cytoskeleton, for example, which is constantly being remodelled. On page 233, Margaret Frame and colleagues review v-Src and its cellular homologue, which can induce both remodelling of the actin cytoskeleton and changes in cell–cell adhesion. Peter Greer (page 278) discusses Fps/Fes and Fer, which might be involved in regulating cytoskeletal rearrangements and some aspects of inside–out signalling. And on page 296, Gregg Gundersen gives us his opinion about why cells keep microtubules in such a highly dynamic state. Finally, Manfred Schliwa (page 291) discusses the structure of the cytoplasm, and debates whether we will ever see its true structure given that, to study it, we need to immobilize this dynamic entity. He comments that, “... Heisenberg's uncertainty principle of quantum mechanics — that the act of observation affects the specimen observed — also applies to the visualization of cytoplasmic structure”. A dynamic issue indeed.