Caveolin-1 coated lipid droplets (LDs) can grow larger than caveolin-1-devoid LDs. A: Confocal images of caveolin-1 deficient human fibroblasts transfected with a Cav1-GFP construct and exposed to oleic-acid (250 µM) for 2 days (medium changed daily). Cells were stained with Nile red and fixed with paraformaldehyde prior to observation. Note that lipid droplets stained by Nile red are present in control caveolin-null cells (arrows) and in caveolin-rescued cells, as cav1GFP+-coated LD (large arrowhead) or cav1GFP−-free LD (small arrowhead). B: Per-cell-based analysis of lipid droplet size in the presence or absence of caveolin. Lipid droplet diameters were determined from microscopy images using Image J software. The distribution of lipid droplet size within individual cells was used to determine mean LD diameter on a per cell basis. Two independent experiments were performed. Individual values corresponding to 50 cells were analyzed by ANOVA. The size of LDs with a Cav1GFP+ coat (2.01 ± 0.75 µm) was significantly higher (P < 0.05) than that of Cav1GFP-free LDs (1.19 ± 0.39) or LDs in control Cav1-null cells (1.11 ± 0.24). C: Diameters of individual LDs (1037) were used to establish size distributions of LD in Control Cav1-null cells (black) or in Caveolin-1-rescued cells without (Cav1GFP−LD in Cav1-rescued cells (red) or with (Cav1GFP+ LD in Cav1-rescued cells (green) a caveolin-1 coat.