Intrabodies: production and promise.

Antibodies are among the most powerful tools in biological research and are presently the fastest growing category of new drug entities. It has long been a dream to harness their power to probe and modulate activities inside living cells. The binding of an antibody to an intracellular molecule has the potential to block, suppress, alter or even enhance the process mediated by that molecule. In particular, intracellular use of antibody fragments can offer an effective alternative to gene-based knockout technologies, potentially with more control and subtlety of outcome. This article outlines progress in the development of intracellular antibodies or intrabodies and highlights their potential, both as drug-discovery tools and as drug entities in their own right.