Learn how to measure transcription rates in vivo.
Primer extension and S1 mapping are useful for determining the concentrations of specific transcripts in a cell at a given time, but they do not necessarily tell us the rates of synthesis of the transcripts. This is because the transcript concentration depends not only on its rate of synthesis, but also on its rate of degradation. To measure transcription rates we can employ other methods including nuclear run-on transcription and reporter gene expression.
See the DNA Molecule in 3-Dimensions