Human cells typically transcribe half of their roughly 20,000 genes into RNA molecules at any given time. Just like with proteins, the function of those RNA species not only relies on their abundance but also their precise localization within the 3D space of each cell. Many RNA molecules convey gene information from the cell's nucleus to the protein-synthesizing machinery distributed throughout the cytoplasm (messenger RNAs or mRNAs), others are components of that machinery itself, while still different ones regulate genes and their expression, or have functions that remain to be discovered. Importantly, many diseases including cancer and neurological diseases have signatures that appear as changes in the abundance and distribution of RNAs.
source https://phys.org/news/2021-03-rna-method-advances-situ-transcriptomics.html
