His group has made important contributions on the functional analysis of epigenetic gene silencing mechanisms by Polycomb-group protein complexes, which play crucial roles in controlling development and cell fate and when deregulated, contribute to cancer formation. Recent work has also focused on the regulation of enzymatic activities of the Polycomb protein complexes by posttranslational modifications and its implications for cancer and DNA repair processes. Using Glioblastoma mouse models and cancer-initiating cancer stem cell lines derived from human Glioblastomas his group is performing in vivo shRNAi and CRISPR library screening to identify critical Polycomb targets and try to define synthetic-lethal interactions. Other focus is on the roles of Polycomb deregulation in Lung cancer and in Mesothelioma. Next to genetic screening these models are being used in drug screens to define new combination therapies involving epigenetic mechanisms.