Reverse transcription polymerase chain reaction
RT-PCR is used to clone expressed genes by reverse transcribing the RNA of interest into its DNA complement through the use of reverse transcriptase, using oligo-DT, which substitutes for the role of primers. Subsequently, the newly synthesized cDNA is amplified using traditional PCR.
https://en.wikipedia.org/wiki/Reverse_transcription_polymerase_chain_reaction