Every human body contains several trillion cells, yet each cell contains an identical DNA sequence. A good way to distinguish one cell from another is by looking at the RNAs they express – something biologists do all the time. The problem is there are thousands of different RNA species forming a cell’s transcriptome. Even with the most advanced imaging methods in biology, scientists can look at only a couple of dozen at a time. And when they focus on just a few RNA species, they’re missing out on a wealth of information.
Source: RNAs Galore | HHMI.org