(ANNOUNCER OPEN):
Researchers at the National Cancer Institute have identified a gene that plays an important role in preventing tumors in mice. Researchers have demonstrated that reducing or eliminating the "H2A.X" gene in mice that lack "p-53"--a well-known tumor-suppressor gene--causes an increase in the number of tumors that develop. Sound confusing? Not really--says Dr. Andre Nussenzweig of the NCI...

(NUSSENZWEIG):
"It's important to understand the mechanism by which normal cells transform into tumor cells, and this work shows that this protein--histone 'H2.X'--is involved in protecting cells from going on to become cancer cells."

(ANNOUNCER CLOSE):
Dr. Nussenzweig says the lack of tumors in mice without "H2A.X" was due to the activity of a protein known as "p-53", which prevents cells containing damaged DNA from dividing until the damage has been repaired--or, in the case of severe damage, causes cells to die. Dr. Nussen- zweig's work is published in this month's [August's] journal "Cell". This is Cherry Graziosi, the National Institutes of Health, Bethesda, Maryland.