The present invention concern a peptidic antagonist of class III semaphorins/neuropilins complexes comprising an amino acid sequence, which is derived from the transmembrane domain of a protein selected in the group consisting of neuropilin-1, neuropilin-2, plexin-A1, plexin-A2, plexin-A3, plexin-A4, Nr-CAM, L1-CAM, integrin Beta 1 and integrin beta 2, and including at least a GxxxG motif, eventually fused to an heterologous sequence a nucleic acid encoding for said peptidic antagonist, a pharmaceutical composition comprising such a peptidic antagonist or a nucleic acid encoding thereof and uses thereof.
