Stefan Constantinescu, MD, PhD is Professor of Molecular and Cell Biology at Université catholique de Louvain, Co-Director of the Ludwig Cancer Research Brussels Laboratories, and Part-Time Professor of Cancer Signalling at the University of Oxford. After earning his MD-PhD at Carol Davila University (Bucharest), he initiated a study that uncovered an outbreak of horizontally transmitted pediatric AIDS in Romania. Trained at MIT's Whitehead Institute, he founded his Brussels lab to study the structure and function of cytokine receptors and blood formation. His group contributed to the discovery of JAK2 V617F mutation myeloproliferative neoplasms (MPNs). He also reported the first JAK1 and TYK2 active mutants now detected in T-leukemia and identified active thrombopoietin receptor mutants in MPNs. Recently, he elucidated how mutant calreticulins induce MPNs demonstrating how a chaperone can become an oncoprotein. An Internal Consultant in Hematology at Saint Luc University Hospital, he has received Belgium’s Five-Year Prize for Basic Medical Sciences and the Tytgat Prize. Elected member of several national academies, he has served as President of FEAM and chairs the Board of SAPEA.