RNA polymerase II transcription and the functional organization of the mammalian cell nucleus.

The study of RNA pol II-mediated transcription regulation has been dominated by molecular biological approaches. Although these methods continue to provide important insights, other approaches are required to insure against an oversimplified view of gene expression. Improvements in EM methods and the development of the confocal light microscope have provided alternative and complementary means of investigating gene regulation. Information on the "context" in which cis- and trans-acting factors operate can be achieved with these techniques. As a result, the spatial compartmentalization of nuclear processes involved in transcriptional and post-transcriptional processing has received considerable attention.