H-Invitational Database (H-InvDB; http://hinv.jp/ ) is an integrated database of all human genes and transcripts that started in an international collaborative research project for establishing a functional annotation database of human full-length cDNAs. Because H-InvDB contains an abundance of information for human transcripts, including not only well-characterized protein-coding transcripts but also those without experimental evidence at the protein level, this will be a useful information resource for identifying novel and uncharacterized human proteins (so-called missing proteins). By extending predicted protein data in H-InvDB, we developed the H-Inv Extended Protein Database (H-EPD; http://hinv.jp/hinv/h-epd/ ). From now on, we plan to carry out a database-driven proteome research that makes full use of H-EPD to promote discoveries in the current and future C-HPP. Furthermore, we will push forward with the integration of genome, transcriptome, and proteome databases using a unique tool for connecting distributed databases and would like to develop a knowledge discovery system by incorporating data mining tools.