PINK1 KO HeLa cells stably expressing mito-Keima were infected with control or shATAD3B. Five days later, cells were treated with DMSO, 200 µM H2O2, or 4 mM 3-NPA for 2 h. Cells were then analyzed and imaged with 458 nm (measuring mitochondria with a neutral pH) and 561 nm (measuring mitochondria with an acidic pH) laser excitation for mito-Keima by confocal microscopy. Scale bar, 10 µm. Quantification of the relative ratio of red to green fluorescence intensity (561nm/458nm) of the cells described in (A). Data are presented as mean ± SD (n = 3 independent experiments, 20 cells per experiment), statistical significance was assessed by two-tailed student's t-test, N.S., not significant, **p < 0.01. 