Use of an antibody, or one of its functional fragments capable of binding to cluster of differentiation (CD)-151 protein and inhibiting the tumor growth for the preparation of a medicament for the treatment of cancer, is claimed. An independent claim is included for a composition for treating cancer, comprising the anti-CD151 antibody as active ingredient, which binds to the protein CD151 and/or to inhibit its metastasis promoting activity. ACTIVITY : Cytostatic. MECHANISM OF ACTION : CD151 protein binder.