D. Confocal imaging analysis depicting COPA puncta (green) formation and co-localization with mTOR (red) in live C2C12 cells transiently expression GFP-COPA and YFP-mTOR in response to nutrient starvation in the presence or absence of BBS (10 µM). Arrows highlight the co-localization of mTOR with COPA. Scale bar, 20 μm. 