text: In RT-PCR, the RNA template is first converted into a complementary DNA (cDNA) using a reverse transcriptase (RT). The cDNA is then used as a template for exponential amplification using PCR. The use of RT-PCR for the detection of RNA transcript has revolutionized the study of gene expression in the following important ways:
  * Made it theoretically possible to detect the transcripts of practically any gene
  * Enabled sample amplification and eliminated the need for abundant starting material required when using northern blot analysis
  * Provided tolerance for RNA degradation as long as the RNA spanning the primer is intact