Ucp2 facilitates engulfment of apoptotic cells. (A) 293T cells were transfected with Ucp2-FLAG, lysed, and separated into the cytoplasmic and the mitochondrial fractions. Erk2 and Porin were used to confirm the cytosolic and the mitochondrial fractions, respectively. (B) LR73 cells were transfected with Ucp2-FLAG and stained with anti-FLAG and anti-AIF antibody. Scale bar, 20 μm. (C, D) LR73 (C) or NIH/3T3 (D) cells transfected with Ucp2-FLAG were stained with anti-FLAG antibody and Mitotracker. Arrowheads indicate the same cells expressing Ucp2-FLAG in all four panels. Scale bar, 20 μm. (E) Ucp2-FLAG was expressed in LR73 cells, stained with TMRE, and analyzed by flow cytometry. Mean fluorescence intensity of TMRE was normalized to the control. (F, G) LR73 cells were transfected with the indicated plasmids and incubated with TAMRA-stained apoptotic thymocytes (F) or 2 μm carboxylate-modified red fluorescent beads (G) for 2 h. The cells were analyzed by flow cytometry. NS, not significant; **P < 0.01, ***P < 0.001.