Switching on the kinase activity of the receptor EphB3, turns this protein from a potential oncogene to a tumour suppressor. The finding, reported in Nature Communications this week, has the potential to provide a new therapeutic strategy for combating lung cancer. Lung cancers are the major cause of cancer-related deaths worldwide with most patients dying within a year, mainly because of the ease at which the tumours spread to to other organs. Dong Xie and colleagues show, in mice, that activation of the kinase function of the receptor EphB3 by its ligands, suppresses the ability of non-small-cell lung cancers to spread. They also identify a novel interacting partner for EphB3, the protein RACK1, which facilitates activation of the kinase and of its tumour suppressive function. This suggests that finding ways to activate the kinase function of this receptor may prove useful in blocking spread of non-small-cell lung cancers, which comprise approximately 80% of all lung cancers.