[1] Johns Hopkins Univ, Sch Med, Dept Pathol, Baltimore, MD 21231 USA
[2] Johns Hopkins Univ, Sch Med, Dept Oncol, Baltimore, MD 21231 USA
[3] Johns Hopkins Univ, Sch Med, Dept Gynecol & Obstet, Baltimore, MD 21231 USA
[4] NCI, Cellular Oncol Lab, Bethesda, MD 20892 USA
[5] Penn State Univ, Coll Med, Dept Microbiol & Immunol, Hershey, PA USA