Rough endoplasmic reticulum (RER) is found in all eukaryotic cells that synthesize and secrete proteins. This includes a wide variety of cells, but some prominent examples include:

* Pancreatic cells: These cells produce digestive enzymes and hormones, requiring extensive protein synthesis.

* Liver cells (hepatocytes): These cells are responsible for detoxifying the body and synthesizing many proteins, including albumin and clotting factors.

* Plasma cells: These cells produce antibodies, a type of protein that helps fight infections.

* Muscle cells: These cells produce muscle proteins, such as actin and myosin, required for contraction.

* Goblet cells: These cells secrete mucus, a protein-rich substance that lubricates and protects tissues.

However, RER is not present in prokaryotic cells. Prokaryotes lack membrane-bound organelles like the RER, and their protein synthesis occurs in the cytoplasm.