miR-20a and LC3 plasmids (GFP-LC3 or mCherry-GFP-LC3) were co-transfected into MDA-MB-231 or MCF7 cells. Nutrient starvation was induced by treating cells with EBSS for 4 h. Fluorescent images of GFP-LC3 or mCherry-GFP-LC3 were acquired by confocal microscope (FV1000; Olympus, Tokyo, Japan). LC3 dots per cell was calculated from 150 cells in each sample.