Fig. 1. (A) Double labeling of Rab proteins (red) and LDs (green) in HepG2 cells. Cells were transfected with cDNA of tagged Rab proteins. LDs were stained with BODIPY 493/503. Rab1, Rab5, Rab7, Rab10 and Rab18 were tagged with FLAG, and Rab2 was tagged with Myc. Rab18 was consistently concentrated around LDs, whereas other Rabs were observed in the vicinity of LDs only infrequently. Bars, 10 µm. (B) The proportion of Rab-positive LDs among all the LDs stained with BODIPY 493/503. Only cells showing positive Rab labeling were selected and counted. More than 500 LDs in 10 random areas were counted in two independent experiments. (C) The proportion of cells in which the Rab-positive LDs were more than 10% of the total detected LDs. Only cells showing positive Rab labeling were selected and counted. More than 30 cells in 10 random areas were counted in two independent experiments. (D) Double labeling of EGFP-tagged Rab18 (green) and LDs (red) in HepG2 cells. The distributions of wild-type Rab18(WT) and GTPase-deficient Rab18(Q67L) were confined to LDs stained with Sudan III, while constitutively GDP-bound Rab18(S22N) was observed diffusely in the cytoplasm. Scale bars: 10 µm.