Watch the cytoskeleton (bright spots).

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Cells expressing green-fluorescent-protein labeled actin (bright spots) are observed as they were chemotaxing towards a micropipette filled with cAMP. The tip of the pipette is moved into different positions as indicated. Images were captured every 18 seconds. From K. Barisic, M. Ecke, C. Heizer, M. Maniak, M. Westphal, R. Albrecht, G. Gerisch, Max-Planck-Institut fur Biochemie, Martinsried, Germany.