Nucleic Acids Research, 2009, Vol. 37, Database issue D363 Figure 2. An example of a PiSite entry. See the main text for details. results (Fig. 2). If the PDB ID of a target protein is already known, then rapid search can be available select- ing the ‘search by PDB ID’ radio button. The interaction viewer shows that the protein has 10 diﬀerent binding states and 9 diﬀerent binding partners. The molecule viewer shows the number of binding partners of each residue, and the residues contacting many partners are colored magenta. Interestingly, this magenta-colored region, including residues 32–42, corresponds to the eﬀector region of a Ras protein. This region of a Ras protein is known as a hot spot and has been identiﬁed as a neutralizing epitope of hRas (27). More mapping result details can be obtained from the download menu. FUNDING Institute for Bioinformatics Research and Development; Japan Science and Technology Corporation (BIRD-JST);