There is not one greatest innovation. For me, there is no question that the greatest advances occurred in the field of genetic engineering, with the cloning, characterisation, manipulation and expression of genes without which we would know essentially nothing about our genetic make-up, hereditary diseases such as muscular dystrophy, cystic fibrosis or diabetes, nothing about viral diseases such as AIDS, or cancer. So I would place on top the sequencing of DNA, PCR and probably, now, the use of siRNA.

Edmond H Fischer is professor emeritus of biochemistry at the University of Washington, and joint recipient of the Nobel Prize in physiology or medicine for discoveries concerning reversible protein phosphorylation as a biological regulatory mechanism