COPI depletion increases autophagosome formation.

<p>(A–F) Transmission electron microscopy analysis of autophagy in MDA-MB-231 cells treated with RF or siRNA against COPB2 for 48 h or imatinib for 24 h. White arrowheads indicating autophagosomes are shown in panels C and E. (B, D, F) High magnification images of boxed areas. Scale bars indicate 2 µm (A, C, E) and 500 nm (B, D, F). (G) Number of autophagosomes per cell was calculated by counting the number of double membrane organelles in 20 or more individual cells. (H) Percentage autophagosomal area was calculated by measuring area covered by double membrane organelles in the cytoplasm of 20 or more individual cells. **, p<0.01; ****, p<0.0001,