High-throughput gene expression profiling--a work-in-progress with great potential for proteomics.

Since the invention of Northern blot profiling more than 30 years ago, scientists have progressed from being able to analyze only a few genes at a time to whole-genome and global differential gene expression profiling. This progress has been made possible by the development of several high-throughput technologies. Such technologies have gained increasing popularity in recent years because of significant discoveries made in the field of proteomics, and have already led to huge advances in the medical field. This article reviews the high-throughput technologies that have been undergoing development during the last two years for the selection of specific cell subtypes in a tissue, for the discovery and identification of all of the genes expressed in a system without pre-selection (open systems), and for the validation of selected genes (closed systems).