Prof Dr. Frank J.T. Staal obtained his bachelor's and master's degrees (both cum laude) in Medical Biology at Utrecht University. He obtained his Ph.D. degree (1993) at the Department of Genetics, Stanford University School of Medicine under the supportive guidance of professors Leonard and Leonore Herzenberg where was taught the intricacies of flow cytometry. His thesis dealt with the transcriptional regulation of HIV expression in T-lymphocytes and involved many functional flow cytometric assays and cell sorting experiments. In 1993 he became a postdoctoral fellow at the Netherlands Cancer Institute for 2 years, after which he moved back to Utrecht University as a fellow of the Royal Academy of Sciences (KNAW) in the laboratory of Professor Hans Clevers. In 2000 he was recruited to Erasmus Medical Center (EMC) Rotterdam to start his own laboratory on human T cell development and became an assistant professor. In 2004 he was appointed associate professor at EMC and expanded his research to Wnt signaling in blood stem cells and T cells, as well as to gene therapy for immune disorders. In 2008 he was recruited to the Leiden University Medical Center (LUMC) and became a full professor of Molecular Stem Cell biology. His inaugural speech (Jan 15th, 2010) was entitled to T or Not to T Together with Jacques van Dongen he heads the LUMC Flow cytometry Core Facility. Frank Staal was trained in biomedicine at the Faculty of Medicine of Utrecht University, The Netherlands. He obtained both his Bachelor's and Master's degrees cum laude from this university and then moved to Stanford University, CA USA, for his Ph.D. degree in Genetics under the supervision of the late Leonard Herzenberg and his wife Leonore Herzenberg. His thesis work involved fundamental and translational aspects of HIV disease. His first postdoctoral work focused on human T cell development, which he extended to genetic mouse models in his second postdoctoral period as a fellow of the Dutch Royal Academy of Sciences under the guidance of Hans Clevers, where he started to work on Wnt signaling. He was recruited by Erasmus Medical School in 2000 to start his own lab focusing on the mouse and human T cell development. During this period at ErasmusMC, Rotterdam, he got interested in gene therapy for SCID, a disease in babies in which T cell development is blocked due to inherited mutations in key developmental genes. In 2007 he was appointed full professor at Leiden University Medical School and moved his lab from Rotterdam to Leiden. He is currently focusing on the clinical implementation of gene therapy for RAG-SCID, other gene therapy approaches with blood stem cells, and basic stem and T cell biology. Fittingly, his appointment is in the Department of Immunohematology, where the late Jon van Rood performed the first bone marrow transplantation for SCID exactly 50 years ago Stem cells The research of Frank J.T. Staal focuses on the molecular regulation of immature T lymphocyte development and hematopoietic stem cell biology. Besides basic aspects of transcriptional regulation and cell signaling in mouse and humans, this knowledge is applied to diagnosis and gene therapy applications of primary human immunodeficiencies as well as to abnormal lymphoid development in acute lymphoblastic leukemias. Translational research leading to novel diagnostic and therapeutic tools is an integral part of his research activities. Key topics: Stem cell biology Immunology T cell development Gene therapy Wnt signaling