Protein sequence data has begun playing a significant role in biology and biochemistry. In the past, protein sequence determination was usually one of the last steps in characterizing a protein. Given the advancements of the Human Genome Project, one can first sequence all the genes and use sequence analysis to infer function using sequence alignment methods. With the development of high-performance sequence comparison methods, researchers have begun making discoveries purely based on sequence comparison. For example, in a surprising discovery made using computational techniques, a human tumor suppressor gene was related to yeast and E. coli DNA repair enzymes. This discovery, albeit the result of a similarity search, helped researchers better study the nature of mutations in oncogenes. As whole genomes from various organisms become available, protein sequence comparison will become indispensable for understanding biological function.