One of the largest challenges in analyzing microarray data is associating the experimental data with the available annotation (e. g. pathway participation, functional annotation, chromosomal location, and literature references). With most current microarray analysis applications, it is not possible to visualize genes based on their functional categorization, chromosomal localization, or tissue expression. For example, show me genes that are transcription factors, are expressed in 'pancreas' and are located on chromosome '1p31'. Integration of gene annotation with analysis techniques is vital to understanding the underlying biological process. To address this need the Biomedical Informatics core has developed Function Express described as follows.