Complex sentence: The Hsp90 cis regulatory element is an RNA element found in the 5' UTR of the Drosophila hsp90 mRNA that is required for increased translational efficiency during the heat shock response.
Split into simpler sentences: The Hsp90 cis regulatory element is an RNA element found in the 5' UTR of the Drosophila hsp90 mRNA. It is required for increased translational efficiency during the heat shock response.