The ER has two parts, the rough ER and the smooth ER. The rough ER has ribosomes attached to it. The proteins made by the ribosomes attached to the rough ER go to the inside the rough ER, called the lumen. After that, they usually go into vesicles, which grow and pinch off from the smooth ER. In most eukaryotes, the vesicles with proteins inside fuse with piles of flattened vesicles called the Golgi bodies, where the proteins inside are changed again.