And that makes sense, because inside our nucleus, in a region known as the nucleolus, we basically synthesize the ribosomal RNA subunits that are needed to create the ribosomes that end up in the rough endoplasmic reticulum. Now, once the proteins in the rough endoplasmic reticulum are synthesized on the cytosol side, we basically take those synthesized proteins, we place them into the Er lumen, and then they travel through the rough Er lumen and eventually into the smooth Er lumen. So now let's discuss the smooth endoplasmic reticulum. Now, by the way, if this is our diagram of the eukaryotic cell, we have the nucleus, we have our rough endoplasmic reticulum that contains these folds. We have slightly smoother, more tubular folds on the smoothie R, and this is our Golgi apparatus. So let's discuss the smoothie R, which is this section here.