d) Intracellular localization of IRGM analysed by confocal microscopy. Cells were stained with antibodies against the indicated proteins or vitally with MitoTracker Red (MTR) where indicated. Images on the right are merged from images on the left. A-L; endogenous IRGM localization in HeLa cells relative to calnexin, MTR, cytochrome c and COX IV. M-O; IRGM localization in primary human macrophages relative to mitochondria visualized with cytochrome c antibody. Scale bars, 5 μm. 