Provide your best answer for the following question. Give ONLY the answer, no other words or explanation.
For example:

Answer: <most likely answer, as short as possible; not a complete sentence, just the answer!>.

The question is: What activity must mRNA do in traveling from DNA to protein synthesis sites in eukaryotic cells that does not occur in prokaryotic cells?
Transcription and translation are separated in eukaryotic cells, so mRNA must be transported from the nucleus to the cytopl