Robust electrotaxis in monolayer, not in isolation. (a-c) MDCK II cells in a sheet showed robust collective electrotaxis in an EF of 200 mV/mm for 6 hours. Red lines with blue arrowheads represent migration paths and direction. (c) Cell migration trajectories with starting positions placed at the origin. (d–f) In a field of the same strength, isolated MDCK II cells did not show electrotaxis. Scale bars, 50 μm. Figures obtained from published paper by the author: CMLS 2012, 69(16):2779–2789.