Localization of IST1 structures with respect to organelle-markers. (A) Dividing HeLa cells were labeled using rabbit anti-IST1 IgG (magenta) as a means to validate the antibody, because IST1 is known to be present in the midbody. IST1-positive midbodies are indicated with arrows. Blue: DAPI. Scale bars: 10 μm. (B) Stimulated emission depletion microscopy (STED) image of moDCs immunolabeled for IST1 (magenta in merge) and ubiquitin or Sec22b (green). Scale bars: 1 μm. (C) Confocal micrographs of moDCs immunolabeled for IST1 (magenta) and the endosomal marker EEA1 (green). Two different z-planes are shown, to show that EEA1 labeling was successful but EEA1 is not present in the IST1-positive structures. The bar graph shows the PCC ± SD (n = 3 donors). The PCC values were compared to 0 using a sample t test. Blue: DAPI. NS: not significant. For the statistical analysis, data distribution was assumed to be normal, but this was not formally tested. Scale bars: 10 μm. (D) Same as C, but now labeled for the nuclear envelope (Lamin A/C; green), endoplasmic reticulum (PDI), the ERGIC (ERGIC53), the Golgi complex (GM130), mitochondria (TOMM20), or autophagosomes (LC3). Scale bars: 10 μm.