Functional cDNA expression cloning: Pushing it to the limit

The 1970s and the following decade are the era of the birth and early development of recombinant DNA technologies, which have entirely revolutionized the modern life science by providing tools that enable us to know the structures of genes and genomes and to dissect their components and understand their functions at the molecular and submolecular levels. One major objective of the life sciences is to achieve molecular and chemical understandings of the functions of genes and their encoded proteins, which are responsible for the manifestation of all biological phenomena in organisms. In the early 1980s, I developed, together with Paul Berg, a new technique that enables the cloning of full-length complementary DNAs (cDNAs) on the basis of their functional expression in a given cell of interest. I review the development, application and future implications in the life sciences of this gene-cloning technique.