GRASP is a public resource for information on the frequencies of 20 amino acids and the atomic composition of their side chains. Currently, it includes information on the proteins of Drosophila melanogaster (fruit fly). In addition to sequence compositions, we have included information on the biological processes, molecular functions, pathways, and gene family for each protein. Access to these data is available through these broad categories as well as by using an exact protein accession identifier. Every query produces a set of proteins along with their amino acid or side-chain atomic compositions. All results can be saved in comma-delimited files for further analysis in other statistical tools. For additional information, please see the section on the Frequently Asked Questions (FAQs).