BFA body formation model. Golgi stacks and TGN/RE are shown in brown and blue, respectively. TGN/RE separations are driven by Sec71, and BFA inhibits Sec71 function. Without BFA, both separations and mergers of TGN/REs occur repeatedly, resulting in Golgi stack-associated TGN/RE being mostly separated in the steady state. After BFA addition, the separation of TGN/RE is greatly decreased, whereas mergers of TGN/RE occur normally, resulting in BFA body formation.