PINK1-YFP R98F (green) is localized to mitochondria in the absence of the mitochondrial depolarizing agent CCCP (carbonyl cyanide-m-chlorophenyl hydrazone). The R98F mutation in PINK1-YFP partially inhibits proteolytic cleavage. When fixed cells are unpermeabilized (not treated with detergent), antibodies to GFP (red) (used to identify PINK1-YFP R98F), and Tom20 (white), a mitochondrial outer membrane marker, are unable to reach and bind their epitopes. PINK1-YFP R98F transfected HeLa cells were treated with DMSO for 3 hrs, fixed with 4% paraformaldehyde and not permeabilized. Primary antibodies used were: anti-GFP polyclonal Ab (Invitrogen) and anti-Tom20 mAb (BD); secondary antibodies used were: Alexa Fluor 594 and 647. Imaging was performed on an LSM510 Meta (Carl Zeiss, Inc) with a 63x 1.4 NA oil differential interference contrast Plan Apo objective. Image contrast and brightness were adjusted in the LSM image browser (Zeiss). This image corresponds to Fig 4c, 4th row from top, and is part of a differential permeabilization assay to determine submitochondrial localization of PINK1 R98F and that is further described in Fig 4c of J Cell Biol, 191: 933-942, 2010. Images in Fig 4 include CIL#s 13733, 13734, 13729, 13730, 13731, 13732, 13717, 13718, 13719, 13720, 13721, 13722, 13723, 13724.