3 Crawling cells exhibit a variety of cell shape dynamics ranging from complex ruffling and bubbling to oscillatory protrusion and retraction. Periodic shape changes during cell migration are recorded in fast moving fish epithelial keratocytes where sticking and slipping at opposite sides of the cell's broad trailing edge generate bipedal locomotion. Barnhart et al. recently proposed a mechanical spring model specifically designed to capture bipedal locomotion in these cells. We extend their

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... el by benchmarking the dynamics of four mechanical configurations against those of crawling keratocytes. Our analysis shows that elastic coupling to the cell nucleus is necessary to generate its lateral motion. We select one configuration to study the effects of cell elasticity, size, and aspect ratio on crawling dynamics. This configuration predicts that shape dynamics are highly dependent on the lamellipodial elasticity, but less sensitive to elasticity at the trailing edge. The model predicts a wide range of dynamics seen in actual crawling keratocytes, including coherent bipedal, coherent non-bipedal, and decoherent motions. This work highlights how the dynamical behaviour of crawling cells can be derived from mechanical properties through which biochemical factors may operate to regulate cellular locomotion. Further information is available [Barnhart etal. Biophys J 98, 933 (2010)]