In brief biologists have overlooked the importance of RNA…that is, until now. Because until recently it was thought that the only useful part of the DNA was the one that encoded proteins and the DNA does not encode proteins then it was deemed junk. Genes (a section of DNA that encodes a protein) are transcribed into RNA that is used to produce the proteins. If the junk DNA is really junk DNA you would expect that only genes would be transcribed into RNA but that is not true. There is a good part of this junk DNA that is transcribed into RNA but not to produce proteins. The RNAinto which not so junk DNA is transcribed is microRNA and regulates the activity of at least a third of the genes that encode protein in humans.
This could explain how is it that the number of genes between species such as C.elegans, the drosophila or humans is so similar when the result is so different. Similar number of genes does not mean similar amount of DNAand thus the difference between species could be due to the difference in the way that they are regulated.
RNA might also have a role in cancer research. RNA interceptor (RNAi) can be used to silence the expression of genes. Recently some researchers at the University of Texas have found how to use RNAi to silence Taxol suppressor genes in tumour cells in the Lung so they can become sensitive again the anti cancer drug Taxol.