Expression Monitoring Using cDNA Microarrays: A General Protocol

As the Human Genome Project nears the completion of the first human sequence, the next great challenge is to elucidate the function of these genes. One route of exploring the function of a gene is by determining its pattern of expression. Various methods are available for detecting and quantitating gene expression levels, including Northern blots (1 ), RNase protection assays (2 ), differential display (3 ), representational difference analysis (1 ), and serial analysis of gene expression (5 ). cDNA microarray technology (6 ,7 ) distinguishes itself from the other methods by allowing one to measure the expression levels of tens of thousands of genes in a single experiment. This capacity allows the expression of entire genomes to be monitored in parallel during different stages of embryonic development, disease progress, or drug response. Microarray technology has therefore attracted a great deal of interest from both academic and commercial sectors.