Dynamics of HPos incorporation into emerging LDs. (A) Starved GFP-HPos–transfected cells were analyzed by video microscopy (Video 1). Pre-LDs (white circles) were followed for 5 min and then cells were loaded with OA (+OA). Red circles indicate LDs emerging after 5 or 9 min. Bar, 2 µm. (B) Quantification of HPos fluorescence intensity and size of pre-LDs (black circles) and emerging LDs (red circles) in three independent experiments as in A. (C) Starved GFP-HPos–transfected cells were treated with increasing OA concentrations for 15 min. Cells were fixed and the sizes and numbers of emerging LDs were quantified. **, P < 0.01; ***, P < 0.001. (D) Starved GFP-HPos–transfected cells (top) were loaded with OA for 15 min (bottom). Cells were fixed, neutral lipids were detected with Nile red (red), and the cells were analyzed by microscopy. Arrows indicate the HPos- and Nile red–positive structures. The insets show high-magnification details of pre-LDs (top and middle) and an emerging LD (bottom) labeled with Nile red. Bars: (top and bottom) 20 µm; (middle) 2 µm; (insets) 0.5 µm. Error bars indicate the standard deviation of at least 60 structures from three independent experiments.