CellX is a database and platform for cooperative research on a particular cell type. Presently, transcriptional regulatory networks (TRNs) are available for a representative set of cell types of relevance to the NIH mission. These TRNs are intended to serve as a basis of user working groups who expand, curate, and use them as training-set TRNs that are transformed via bioinformatics, cell modeling, and gene expression and proteomic data to a TRN tailored for a particular cell line. For more information, contact Peter J. Ortoleva, Director of the Center for Cell and Virus Theory, at 812-855-2717.