Many dynamic phenomena in cells are driven by cytoskeletal motor proteins. I will discuss examples of mechanical oscillations that occur in living cells and which can be described by simple physical models. The first example concerns the dynamics of the mitotic spindle during cell division which results in daughter cells of different size. The dynamics and force balance in the spindle under these conditions gives rise to oscillations. The theoretical analysis of these oscillations reveals the properties of force generators involved and provides information on the dynamic organization of spindle repositioning. A second example concerns hair bundles of mechanosensory cells. It has been shown that these structures oscillate spontaneously, which provides a frequency selective amplification mechanism of periodic mechanical stimuly. The interplay of calcium-regulated motor molecules and mechanosensitive ion channels provides a simple framework which allows for a quantitative description of the mechanical properties of active hair bundles, if fluctuations are taken into account.
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