Slimane Ait‑Si‑Ali is a Principal Investigator (Directeur de Recherche) at the Centre National de la Recherche Scientifique (CNRS). He received his PhD in 1998 from University Pierre et Marie Curie in Paris, France. He joined the CNRS in 2000 after his post-doctoral training in Alan P. Wolffe’s laboratory at the National Institutes of Health (Bethesda, Maryland, USA). He was awarded an ACI-Jeunes Chercheurs starting grant as a Junior Group Leader and the Prix Coup d’Elan à la Recherche Française from the Fondation Bettencourt-Schueller in 2005. He headed a young team in the Institut André Lwoff (IAL, Villejuif, France), before joining the Epigenetics and Cell Fate department in 2009. His team is one of the 6 founding teams of the department. He is mainly interested in gene expression regulation by chromatin modifications, especially lysine methylation. For the last 10 years, his team’s work was dedicated to the study of the epigenetic basis underlying stemness and differentiation, to identify new determinants of normal and pathological cell fate changes and to tackle important mechanistic aspects behind this. For example, he uncovered the essential role of chromatin architecture in the determination of oncogenic programs through functional links between gene expression, epigenome, 3D genome and nuclear mechanics.