Pre-processing of microarray data and analysis of differential expression.

Microarrays have become a widely used technology in molecular biology research. One of their main uses is to measure gene expression. Compared to older expression measuring assays such as Northern blotting, analyzing gene expression data from microarrays is inherently more complex due to the massive amounts of data they produce. The analysis of microarray data requires biologists to collaborate with bioinformaticians or learn the basics of statistics and programming. Many software tools for microarray data analysis are available. Currently one of the most popular and freely available software tools is Bioconductor. This chapter uses Bioconductor to preprocess microarray data, detect differentially expressed genes, and annotate the gene lists of interest.