The current explosive progress in molecular biological research can be definitively traced to the development of molecular cloning technology. The ability to insert specific gene sequences into cloning vectors and their subse­ quent expansion is the cornerstone of modem molecular biology. A direct practical outcome of molecular cloning technology is its application to ex­ press specific recombinant genes. Currently, recombinant gene products are used in a wide spectrum of applications, including gene therapy, production of bioactive pharmaceuticals, synthesis of novel biopolymers, in agriculture and animal husbandry, and so on. A fundamental requirement for successful recombinant gene expression is the design of the cloning vector and the choice of the host organism for expression. Recombinant Gene Expression Protocols grows out of the need for a laboratory manual that provides the reader the background and rationale, as well as the practical protocols for the preparation of "expression constructs" and their introduction into appropriate host cells and/or organisms. The chap­ ters in this book are grouped by their expression hosts, including E. coli, yeast, mammalian cells, nonmammalian eukaryotes such as plants, Xenopus, and insects, as well as in transgenic organisms. In-depth information is presented on the important characteristics of expression cloning vectors and the various methods for efficiently introducing expression constructs into target cells and/ or organisms. Throughout Recombinant Gene Expression Protocols, the authors have consistently striven for a balanced presentation of both background informa­ tion and actual laboratory details.