Mitochondrial fragmentation does not induce Parkin accumulation independently of mitochondrial membrane potential. (a–d) HeLa cells cotransfected with YFP-Parkin (green) and with empty vector (a), vMIA (b), or Drp1 K38A (c). Cells were treated with 10 μM CCCP (a, right, and c) or DMSO (a, left, and b) for 1 h. Mitochondria were immunostained for cytochrome c (red). The bottom two panels in each column show an enlarged view of the boxed regions. (d) YFP-Parkin colocalization with mitochondria were scored as in Fig. 1 f. Error bars indicate standard deviation of at least three replicates. Bars, 5 μm.