The Nuclear Protein Database (NPD) contains information on proteins that are localized to the nuclei of vertebrate cells. Over 1000 vertebrate proteins, mainly from mice and humans, are included. When known, the sub-nuclear compartment where the protein was found is reported. The NPD also provides information on a protein's amino acid sequence, predicted size, and isoelectric point, as well as any repeats, motifs, or domains within the sequence. Where appropriate, links to other databases are provided.