ST. LOUIS -- A $156 million grant for DNA sequencing at the Washington University School of Medicine is part of an effort to unlock the mystery of the origins of cancer within the body, university officials said Monday.

The four-year grant is one of only three awarded Monday by the National Human Genome Research Institute (NHGRI). The Baylor College of Medicine in Houston and the Broad Institute at the Massachusetts Institute of Technology/Harvard University are the other recipients.

Washington University scientists were part of the collaboration that in 2000 produced the first human genome sequence -- a molecular map of our species. The new grant is aimed at taking that that work a step further.

Genetic errors that accumulate in normal cells can lead to a transformation that eventually causes cancer. Washington University officials said an estimated 300 genes involved in cancer are already known.

Scientists believe a more in-depth search could identify other genes that determine, for example, how aggressive a particular tumor is, or what drugs might be best-suited to treat it.