Epigenetic pathways contribute to cancer development and progression. These pathways act via proteins that modulate chromatin structure and gene expression, and can thereby give pro-proliferative and anti-apoptotic properties selected for in cancer. In total ~400 factors are known that either modify chromatin directly as epigenetic ‘writers’ (DNA methyltranserases, histone methyltransferases, acetyltransferases, kinases, ubiquitinases) and ‘erasers’ (histone demethylases, deacetylases, phosphatases, deubiquitinases) or indirectly by moving nucleosomes (‘remodelers’) or binding to the modifications set by the ‘writers’ (‘readers’; e.g. bromo, PHD, chromo, tudor domains). Small molecules inhibiting several chromatin modifying enzymes have been developed, and HDAC inhibitors and DNA methyltransferase inhibitors are approved drugs. While DNA methyltransferases and histone deacetylases are well-established drug-targets, the majority of the ~400 chromatin modifiers is not studied in cancer. Furthermore, the functional link between genetic alterations of the genes encoding these enzymes and increased proliferation in a cancerous state is less well established.Here we propose to generate and apply tools to systematically study these proteins in cancer using epigenome-wide knock-down studies and small molecule probes. This project directly benefits from the experience at the Broad Institute, where Stefan Kubicek worked for 3.5 years, which allowed him to bring to CeMM a library of knock-down constructs targeting all chromatin proteins in collaboration with the Broad RNAi platform. Similarly, his work on histone demethylases has yielded interesting probe compounds, and his continuing collaboration is recognized by his continuing status as a Remote Associate Researcher of the Broad Institute Chemical Biology Program. Stefan Kubicek started at CeMM in August 2010 and funding of this EPICAL proposal will allow to further integrate his career in the European research space.