Depletion of COPI protein inhibits cis to trans cisternal maturation. Depletion of COPI protein inhibits cis to trans cisternal maturation. Ret1-aid (A) and Sec21-aid (B) cells expressing Mnn9–mCherry (cis, magenta) and Gnt1–GFP (medial, green) were grown to a mid-logarithmic phase in synthetic medium with or without 1 mM NAA at 30°C and observed by SCLIM. Representative 3D images of cells with (lower panels) or without (upper) NAA are shown. Dashed lines indicate the edge of cells. Right panels show 3D time-lapse images of the indicated areas. Scale bars: 1 µm. Representative images from at least five independent cells are shown. Midori Ishii et al. J Cell Sci 2016;129:3251-3261 © 2016. Published by The Company of Biologists Ltd