title: Pulling back to move forward.
abstract: Animal cells can change shape and move by using actin polymerization to drive plasma membrane protrusion. Giannone and coworkers (this issue of Cell) describe how cells periodically pull back on these protrusions in order to sense and respond to the rigidity of their environment.
authors.affiliation: Ludwig Institute for Cancer Research and Department of Biochemistry and Molecular Biology, University College London, 91 Riding House Street, London W1W 7BS, United Kingdom.
authors.forename: Anne J
authors.initials: AJ
authors.lastname: Ridley
mesh_terms: D000199:Actins / Q000502:physiology*; D000818:Animals; D002465:Cell Movement / Q000502:physiology*; D022081:Cell Surface Extensions / Q000502:physiology*; D005109:Extracellular Matrix / Q000378:metabolism; D006801:Humans; D016023:Integrins / Q000378:metabolism; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D011108:Polymers / Q000378:metabolism; D011554:Pseudopodia / Q000502:physiology; D015398:Signal Transduction / Q000502:physiology
chemical_list: D000199:Actins; D016023:Integrins; D011108:Polymers; D009219:Myosin-Light-Chain Kinase