aLaboratory of Pathology

bNeuro-Oncology Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA

Correspondence to Mark R. Gilbert, MD, Chief, Neuro-Oncology Branch, CCR Deputy Director, Center for Cancer Research, National Cancer Institute, Building 82, Room 235A, Bethesda, MD 20814, USA. Tel: +1 240 760 6023; fax: +1 301 480 5124; e-mail: [email protected]