Mutations of MAP 2 K 1 are frequent in pediatric-type follicular lymphoma and result in ERK pathway activation Running title : Genetics of pediatric-type follicular lymphoma

Institute of Pathology and Neuropathology, Eberhard Karls University of Tübingen and Comprehensive Cancer Center, University Hospital Tübingen, Tübingen, Germany Hematopathology Unit, Hospital Clínic, Institut d’Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), CIBERONC, Barcelona, Spain Hematopathology Section, Laboratory of Pathology, National Cancer Institute, Bethesda, MD, USA Department of Cellular Pathology, Barts and The London NHS Trust, London, UK Pathology Department, Instituto Portugues de Oncología, Lisboa, Portugal Department of Histopathology, Guy's and St Thomas Hospitals, London, UK Department of Pathology, All Wales Lymphoma Panel, University Hospital of Wales, Cardiff, UK Institute of Pathology, University of Würzburg, Germany and Comprehensive Cancer Center Mainfranken (CCC MF), Germany Department of Clinical Pathology, Robert-Bosch-Hospital and Dr. Margarete Fischer-Bosch Institute of Clinical Pharmacology, Stuttgart, Germany