One possible explanation for the high incidence of ovarian leiomyosarcomas is that ovarian stromal cells may be coincidentally infected after intrabursal injection of Ad5-CMV-Cre and that the combined loss of both Brca1 and p53 renders this population of cells more susceptible to transformation than the ovarian surface epithelium. The gene discussed is BRCA1; the disease is ovary leiomyosarcoma.