However, in the presence of metastasis CD26 expression was reduced or absent in 50% of cases (Dinjens et al. 1990) while CD 13 showed very low or no activity (Carlsson et al. 2003), suggesting that loss of these ectoenzyme may be involved in the development of metastatic disease (Dinjens et al. 1990; Carlsson et al. 2003). This evidence concerns the gene DPP4 and metastatic neoplasm.