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Cytoskeleton elasticity and dynamics during cell motility: AFM observation of PtK2 cells in the pico-newton force regime

Atomic force microscopy (AFM) (Binnig et al 1986) has been successfully employed for studies in the field of cell biology over this past decade (as reviewed by You and Lu (1999) for example). The technique, which offers superior spatial resolution when compared with conventional optical microscopy, is capable of generating true 3D topographic images. Further, observation may be undertaken with specimens fully submerged in native physiological solutions, so that dynamic processes in live systems can be followed with unprecedented resolution. Past examples of this latter endeavour include observations of actin filament dynamics in living glial cells by Henderson and co­ workers (1992), real-time observation of viral exocytosis in monkey kidney cells (Ohnesorge et al (1997)), and the visualisation of mitosis in mouse osteoblasts (Kuznetsov et al (1997)). Such studies underscore the powerful capability of AFM to undertake exacting measurements across a spectrum of cell lines.