And that's exactly why once our nucleolus synthesizes those incomplete ribosomes, those ribosomes can then be placed inside this Er to basically embed the ribosomes inside the membrane of the Er. And then those ribosomes can synthesize our proteins. Now, what about this section, the smooth Er shown by region five. This region also contains these membranes, but they do not contain ribosomes. And so that means this smooth Er isn't directly involved in synthesized proteins. Instead, the smooth Er functions to produce lipids or fats, as well as to detoxify toxins and drugs.