The rough endoplasmic reticulum (RER) is found throughout the cytoplasm, but it is often located near the nucleus.

Here's why:

* Proximity to the nucleus: The RER is the site of protein synthesis, and ribosomes on its surface translate mRNA transcribed from DNA in the nucleus. This close proximity facilitates the quick transport of mRNA from the nucleus to the ribosomes on the RER.

* Cytoplasmic distribution: The RER extends throughout the cytoplasm, forming a network of interconnected membranes. This network allows for the efficient transport of newly synthesized proteins to other parts of the cell.

So, while the RER is often near the nucleus, it's important to remember that it exists throughout the cytoplasm to carry out its vital functions.