Eph receptor tyrosine kinases have an important role in tissue assembly and the guidance of migrating cells in which they mediate contact-dependent repulsion upon interaction with cells expressing ephrin ligands. However, in other contexts Eph-ephrin interactions can instead promote cell invasion and adhesion. Both of these distinct responses may underlie the remodelling or maintenance of the organisation of many tissues, including the vasculature. However, it is not known how such diverse responses to Eph receptor activation are regulated. Since FGF receptors promote cell migration in many developing tissues and in cancer, we have explored the possibility that FGF receptor could act antagonistically to the cell repulsion activity of Eph receptors. We have found that activation of FGF receptor inhibits the restriction of cell intermingling by EphB-ephrinB interactions. Furthermore, we have found that there is cross-talk between these receptor systems in which FGF receptor activation alters the activation of EphB receptor by ephrinB ligand. This talk will discuss the results of time lapse movies and biochemical studies in which we are dissecting how cross-talk from FGF receptor modulates the response of cells to Eph receptor activation.