In a study in mice, scientists have compensated for mutations in the Brca1 gene that can lead to cancer by deleting a second gene, which then lessens the probability of cancer. Mice Brca1-associated mammary tumors have significant similarities to human BRCA1- associated (BReast CAncer 1, early onset) breast cancer in regard to tumor aggressiveness, high incidence, mutations and genetic instability. The study, led by scientists at National Cancer Institute (NCI), part of the National Institutes of Health, and their colleagues, appeared online April 1, 2010 and in print April 16, 2010, in the journal Cell.