The invention concerns the use of stabilized oligonucleotides comprising
at least an octamer motif of the type:
5'-purine-purine-CG-pyrimdine-pyrimidine-X.sub.1X.sub.2-3' wherein the
pair X.sub.1-X.sub.2 is AT, AA, CT or TT, for preparing a medicine with
antitumour activity.