Ezrin/radixin/moesin (ERM) proteins form crosslinks between cortical actin filaments and the plasma membrane. New findings indicate that they may also bind to the tumour-suppressor protein hamartin, thereby regulating Rho GTPases, the actin-based cytoskeleton and cell adhesion. Loss of hamartin function disrupts cell adhesion, which may contribute to the formation of tumours in individuals carrying hamartin mutations.