Furthermore, we have shown that CD26 expressed on T-anaplastic large cell lymphoma KARPAS299 cells was involved in cell adhesion and tumorigenicity [11] and that KARPAS299 tumor growth was efficiently suppressed by our anti-CD26 monoclonal antibody 1F7 [12], indicating that CD26 is also a suitable therapeutic target for T-cell malignancies. This evidence concerns the gene DPP4 and neoplasm.