(A) An INS1 cell expressing mtPA‐GFP and co‐labeled with TMRE. The two mitochondria fused 20 s after photoactivation (arrow in '20 s'). Then, a voltage difference was established between the two poles (120 s) and they were later physically separated (120 s). The pattern is qualitatively similar to that shown in Figure 3Bi. Scale bar, 2 μm. 