Abstract: This invention relates to extracellular protein-protein interactions and their possible therapeutic uses. More particularly, this invention describes the interaction between Draxin, particularly fragments binding to ?-Netrins comprising SEQ ID NO.: 1, 2 or 3, and variants thereof, with ?-Netrins, and the use of this interaction to disrupt ?-Netrin/Netrin receptor interactions. The invention also relates to diagnostic and/or therapeutic uses of Draxin or fragments or variants thereof, as well as to an antibody against Draxin inhibiting binding of Draxin to ?-Netrins. Further, the invention relates to fragments of ?-Netrins, in particular Draxin-binding Netrin1-fragments comprising SEQ ID NO.: 51 and variants thereof, as well as to an antibody against ?-Netrins inhibiting binding of ?-Netrins to Netrin receptors.